Health action process approach

The Health Action Process Approach (HAPA) is a social-cognitive model developed by Ralf Schwarzer in the early 1990s that conceptualizes the adoption, initiation, and maintenance of health behaviors as a structured process divided into two main phases: a pre-intentional motivational phase leading to the formation of intentions, and a post-intentional volitional phase focused on planning, action initiation, and sustained behavior change.^[1]^[2] In the motivational phase, individuals develop behavioral intentions through three primary constructs: risk perceptions, which involve awareness of personal vulnerability to health threats; outcome expectancies, encompassing beliefs about the positive and negative consequences of engaging in a health behavior; and action self-efficacy, which reflects confidence in one's ability to form an intention despite barriers.^[1]^[2] These elements collectively predict the strength of an intention to adopt a health behavior, such as exercising regularly or adhering to medication, though intentions alone often fail to translate into action without further volitional strategies.^[3] The volitional phase bridges the intention-behavior gap by emphasizing self-regulatory processes, beginning with the development of action plans—specific if-then strategies detailing when, where, and how the behavior will occur—and progressing to the initiation of action, maintenance of the behavior over time, and recovery from setbacks.^[1]^[2] Coping self-efficacy and recovery self-efficacy play pivotal roles here, supporting persistence in the face of obstacles and relapse prevention, respectively, while barriers and resources further influence successful implementation.^[3] Central to HAPA across both phases is self-efficacy, which meta-analytic evidence shows exerts small-to-medium effects on intentions, planning, and actual behavior, with stronger impacts in domains like physical activity compared to dietary changes.^[3] The model distinguishes itself from other theories, such as the Theory of Planned Behavior, by integrating motivational and volitional determinants and highlighting the need for explicit planning to enhance behavior change efficacy.^[2] HAPA has been applied to diverse health behaviors, including smoking cessation, weight management, cancer screening adherence, and chronic disease self-management, with empirical support from longitudinal studies and structural equation modeling demonstrating its predictive validity in interventions worldwide.^[1]^[2]^[3]

Overview and Background

Definition and Purpose

The Health Action Process Approach (HAPA) is a social-cognitive model designed to explain, predict, and facilitate the adoption, initiation, and maintenance of health behaviors. Developed by Ralf Schwarzer, it conceptualizes behavior change as a structured process comprising two main phases: a pre-intentional motivational phase, which focuses on forming the intention to act, and a post-intentional volitional phase, which addresses the translation of intentions into sustained actions. This framework integrates elements from social-cognitive theory, emphasizing the role of psychological constructs in bridging the gap between motivation and actual behavior change.^[1]^[2] The primary purpose of HAPA is to provide a theoretical basis for designing effective health interventions by highlighting the distinct processes involved in goal setting and goal pursuit. Unlike simpler models that primarily focus on intention formation, HAPA underscores the necessity of volitional strategies to overcome barriers such as lapses and relapses, thereby improving long-term adherence to health behaviors like physical exercise, dietary changes, or medication compliance. It aims to empower individuals through enhanced self-regulation, recognizing that intentions alone are insufficient for behavior maintenance without supportive cognitive and planning mechanisms.^[4]^[1] Central to HAPA's definition is its distinction between motivational factors—such as risk perception, outcome expectancies, and action self-efficacy—that drive intention, and volitional factors—like planning, action control, and maintenance self-efficacy—that enable implementation and persistence. This phased approach serves to guide interventions that target both phases sequentially, promoting a comprehensive understanding of how individuals progress from awareness to habitual action in health contexts.^[2]^[4]

Historical Development

The Health Action Process Approach (HAPA) emerged in the early 1990s as a response to limitations in existing health behavior theories, which often overlooked the distinction between forming intentions and enacting behaviors. Ralf Schwarzer, a health psychologist at Freie Universität Berlin, introduced the model in 1992 through a seminal book chapter that synthesized social cognitive theory—particularly Albert Bandura's concept of self-efficacy—with elements of stage-based models like the Transtheoretical Model.^[5] In this foundational work, titled "Self-Efficacy in the Adoption and Maintenance of Health Behaviors: Theoretical Approaches and a New Model," Schwarzer proposed a two-phase structure: a pre-intentional motivational phase driven by risk perceptions, outcome expectancies, and task self-efficacy to form intentions, and a post-intentional volitional phase emphasizing action initiation and maintenance through coping self-efficacy.^[5] This hybrid approach aimed to bridge the intention-behavior gap, a common critique of models like the Theory of Planned Behavior.^[5] Subsequent refinements in the late 1990s and early 2000s expanded HAPA's scope and empirical grounding. Schwarzer's 1999 article in the Journal of Health Psychology elaborated on self-regulatory processes, integrating planning as a key volitional mediator to translate intentions into sustained actions.^[6] By 2001, in a paper published in Current Directions in Psychological Science, Schwarzer further clarified the social-cognitive mechanisms, highlighting how self-efficacy facilitates progression through motivational and volitional stages in diverse health contexts like exercise adoption. These developments positioned HAPA as a dynamic framework adaptable to individual differences in behavior change. A pivotal evolution occurred in 2008 with Schwarzer's comprehensive review in Applied Psychology: An International Review, which synthesized over a decade of research and formalized HAPA as a predictive and interventional model.^[7] This iteration introduced nuanced constructs, including action self-efficacy for initiation, coping self-efficacy for barriers, and recovery self-efficacy for relapses, alongside strategic planning (e.g., if-then plans) to enhance volitional control.^[7] Empirical validations in this work demonstrated HAPA's efficacy across behaviors such as sun protection and dietary adherence, with meta-analytic support later confirming its constructs' predictive power (e.g., self-efficacy explaining 10-20% variance in behavior).^[3] Ongoing collaborations, including with Aleksandra Luszczynska, have since incorporated cultural adaptations and digital interventions, ensuring HAPA's relevance in global health psychology.^[8]

Structure of the Model

Pre-Intentional (Motivational) Phase

The pre-intentional phase, also known as the motivational phase, of the Health Action Process Approach (HAPA) focuses on the formation of behavioral intentions to adopt or change health behaviors, targeting individuals who are not yet committed to action. This phase emphasizes psychological processes that lead from deliberation to goal-setting, distinguishing between those who contemplate change and those who proceed to planning. It posits that intention serves as the proximal determinant of subsequent behavior, but its formation requires specific cognitive and affective constructs to overcome inertia.^[9]^[10] Central to this phase is risk perception, which involves an individual's awareness of health threats, comprising two components: perceived vulnerability (the likelihood of experiencing a negative health outcome) and perceived severity (the anticipated consequences of that outcome). For instance, a person might recognize their susceptibility to cardiovascular disease due to sedentary habits and view it as a serious threat to longevity. Risk perception initiates motivation by creating a sense of concern, prompting consideration of protective actions, though it typically exerts only a small effect on intention formation compared to other factors.^[11]^[9] Outcome expectancies refer to beliefs about the anticipated benefits and costs associated with performing a health behavior, balancing positive outcomes (e.g., improved well-being from regular exercise) against potential drawbacks (e.g., time constraints). These expectancies influence intention by motivating individuals to weigh the pros and cons, with positive expectancies generally promoting goal commitment. Empirical evidence from a meta-analysis of 95 studies indicates that outcome expectancies have a small-to-medium effect on intentions, stronger for physical activity behaviors than dietary changes.^[9]^[10] The most influential construct in this phase is action self-efficacy, defined as the optimistic self-belief in one's ability to initiate a behavior despite barriers, such as confidently starting a new exercise routine. It acts as the strongest predictor of intentions, fostering the confidence needed to form goals. Meta-analytic findings confirm a small-to-medium association between action self-efficacy and intentions, with consistent effects across diverse health domains, underscoring its role in bridging awareness to commitment.^[11]^[9] Collectively, these constructs interact to produce an intention, which HAPA views as a deliberate commitment to act (e.g., "I intend to exercise three times a week"). While intentions are necessary, the model highlights that the motivational phase alone often results in the intention-behavior gap, necessitating progression to the volitional phase for enactment. This framework has been supported by longitudinal studies showing that motivational factors account for notable variance in intentions across behaviors like smoking cessation and physical activity adoption.^[9]^[10]

Post-Intentional (Volitional) Phase

The post-intentional (volitional) phase of the Health Action Process Approach (HAPA) addresses the transition from behavioral intention to actual health behavior enactment and maintenance, bridging the well-documented intention-behavior gap through self-regulatory strategies. This phase emphasizes volitional processes that enable individuals to initiate actions, persist despite barriers, and recover from setbacks, recognizing that intentions alone often fail to produce sustained change without supportive mechanisms.^[12] Key to this phase is the integration of planning and self-regulatory efforts, which transform abstract goals into concrete behaviors while adapting to environmental and personal challenges.^[1] Central to the volitional phase are action planning and coping planning, which serve as mediators between intention and behavior. Action planning involves formulating specific plans specifying when, where, and how to perform the intended behavior, such as scheduling a 30-minute walk every weekday morning at a local park. Coping planning involves if-then strategies to anticipate potential obstacles and devise alternative actions, for instance, planning an indoor workout if rain occurs, thereby fostering resilience against disruptions.^[3]^[13] Together, these planning constructs promote behavior initiation and are particularly effective in contexts like physical exercise adherence among cardiac rehabilitation patients, with meta-analytic evidence showing small-to-medium effects on behavior. Action control further supports the volitional phase by providing ongoing self-regulation to monitor progress and align actions with intentions. This includes self-observation (e.g., tracking daily fruit intake via a journal), discrepancy evaluation (comparing actual versus planned behavior), and corrective efforts to sustain momentum.^[12] Action control acts as a proximal predictor of behavior, mediating the effects of planning, as demonstrated in studies on dental flossing where it accounted for significant portions of variance in routine formation. By facilitating attention to goal-relevant cues and suppressing competing impulses, such as cravings during smoking cessation, action control ensures persistence in health-promoting activities.^[1] Self-efficacy plays a pivotal role in the post-intentional phase, evolving from its motivational roots to support volitional execution through subtypes like maintenance self-efficacy and recovery self-efficacy. Maintenance self-efficacy refers to confidence in exerting effort to overcome barriers during ongoing behavior, such as believing one can resist social temptations to skip exercise. Recovery self-efficacy, meanwhile, involves optimism about rebounding after lapses, like resuming a diet after a holiday indulgence, and has been shown to predict 11-46% of variance in behaviors like smoking reduction.^[12] These efficacy beliefs not only drive planning and control but also interact with situational factors, such as social support, to enhance long-term adherence in areas like dust mask use for pollution protection.^[13] Overall, the volitional phase operates dynamically, with planning initiating behavior, action control maintaining it, and self-efficacy providing the motivational fuel for both, ultimately leading to robust health outcomes.^[3] This structured approach has been applied across diverse behaviors, underscoring its utility in interventions targeting chronic disease management.

Central Constructs

Self-Efficacy

In the Health Action Process Approach (HAPA), self-efficacy represents an individual's optimistic belief in their capability to initiate, execute, and maintain health behaviors despite potential obstacles.^[1] This construct, rooted in Albert Bandura's social cognitive theory, is distinguished by phase-specific forms that operate across the model's motivational and volitional stages, influencing the progression from intention formation to sustained action. Unlike general self-efficacy, HAPA emphasizes task-specific confidence tailored to health behavior challenges, such as exercising regularly or adhering to a medication regimen. Action self-efficacy, a key variant in the pre-intentional (motivational) phase, refers to the perceived ability to take initial steps toward a health goal, thereby serving as a direct predictor of intention formation. It often mediates the relationship between outcome expectancies—beliefs about the benefits of the behavior—and intentions, with stronger effects observed in individuals with prior experience.^[1] For instance, high action self-efficacy can amplify motivation to quit smoking by fostering confidence in the first attempt to abstain. Risk perceptions may indirectly bolster this form of self-efficacy by heightening awareness of vulnerabilities, prompting proactive planning. In the post-intentional (volitional) phase, coping self-efficacy emerges as confidence in managing barriers and relapses to sustain behavior over time.^[1] This includes recovery self-efficacy, which specifically addresses the ability to rebound after lapses, such as resuming physical activity following a period of inactivity. These volitional self-efficacies facilitate planning strategies and action control, determining the effort invested and perseverance against temptations. For example, in dietary interventions, coping self-efficacy predicts long-term adherence by enabling individuals to navigate social or environmental challenges. Meta-analytic evidence confirms self-efficacy's central role in HAPA, with small-to-medium effects on intentions and behavior maintenance across diverse health domains like exercise and preventive screenings.^[3] Interventions targeting self-efficacy, such as mastery experiences or verbal persuasion, have demonstrated moderate to large effects on behavior change, underscoring its malleability and practical utility.

Planning Strategies

In the Health Action Process Approach (HAPA), planning strategies serve as pivotal self-regulatory mechanisms in the post-intentional (volitional) phase, facilitating the translation of intentions into actual health behaviors. These strategies address the common intention-behavior gap by providing structured cognitive processes that specify the timing, context, and execution of actions, thereby enhancing initiation, maintenance, and recovery from setbacks. Planning is influenced by action self-efficacy, which empowers individuals to formulate and adhere to these plans, and it operates continuously rather than as a one-time event.^[11] Action planning involves the formation of detailed, if-then plans that outline the when, where, and how of performing a desired behavior, transforming abstract intentions into concrete, proximal goals. For instance, an individual intending to increase physical activity might plan: "After breakfast on weekdays, I will walk for 30 minutes in the nearby park." This process, often referred to as implementation intentions in broader literature, is guided by self-efficacy and helps automate behavior initiation through situational cues. Empirical studies demonstrate that action planning significantly predicts behavior performance, with meta-analyses indicating small effects across various health domains such as exercise and dietary changes.^[3] Coping planning complements action planning by focusing on anticipated barriers and developing compensatory strategies to overcome obstacles or temptations, ensuring behavioral maintenance over time. Examples include devising alternatives like "If it rains during my walk, I will exercise indoors with a workout video" or using distraction techniques to manage cravings in smoking cessation. This proactive approach fosters resilience against disruptions, such as environmental challenges or lapses in motivation, and is particularly effective when combined with action planning. Research, including longitudinal interventions, shows that coping planning mediates the intention-behavior relationship more robustly than action planning alone, with notable effects in physical activity adherence.^[13] Together, these planning strategies underscore HAPA's emphasis on volitional control, with self-efficacy acting as a core facilitator that varies in depth—from superficial to highly elaborated plans—depending on individual resources. Seminal work by Sniehotta et al. (2005) integrated these elements into HAPA's framework, highlighting their role in multi-phase interventions for behaviors like sun protection and medication adherence. Meta-analytic evidence confirms their efficacy in diverse populations, though outcomes are moderated by contextual factors such as social support.

Applications and Evidence

Interventions Based on HAPA

Interventions based on the Health Action Process Approach (HAPA) systematically target the model's two phases to promote health behavior change, integrating motivational strategies to form intentions and volitional strategies to enact and maintain behaviors. In the pre-intentional (motivational) phase, interventions enhance risk perceptions, outcome expectancies, and action self-efficacy to foster strong intentions, often through tailored persuasive communications that emphasize personal coping capabilities over fear-based appeals. Self-efficacy emerges as a core mediator, with studies showing it predicts intentions with small-to-medium effect sizes (r ≈ 0.30–0.40). For example, educational programs for smoking cessation among university students have used HAPA to boost outcome expectancies and self-efficacy, leading to increased quit intentions via structured sessions and self-assessment tools.^[1]^[13]^[9] In the post-intentional (volitional) phase, HAPA interventions focus on bridging the intention-behavior gap through action planning, coping planning, maintenance self-efficacy, and action control, such as self-monitoring and relapse prevention techniques. Participants are typically guided to develop specific action plans (e.g., "if-then" scripts for exercise routines) and coping strategies to handle barriers, with maintenance self-efficacy supporting long-term adherence (r ≈ 0.25–0.35 for behavior prediction). A notable application is in dental flossing promotion, where brief self-regulatory interventions in Poland and India improved flossing frequency among students and adults by integrating planning and self-efficacy enhancement, yielding significant behavior increases (p < 0.01) mediated by these constructs. Similarly, for hypertension management, HAPA-based teaching interventions have enhanced self-care behaviors like medication adherence and physical activity through eight-week programs emphasizing planning and recovery self-efficacy.^[1]^[9]^[13] HAPA interventions have demonstrated efficacy across diverse health domains, particularly for chronic conditions, as evidenced by meta-analyses and reviews. A 2019 meta-analysis of 95 studies found that volitional factors like planning and action control explain additional variance in behaviors beyond intentions, with overall small-to-medium effects on outcomes such as physical activity and dietary adherence. In physical activity promotion, the Australian My Health for Life program—a six-month intervention for at-risk adults—targeted HAPA constructs via SMART goal-setting and facilitator support, resulting in sustained increases in fruit/vegetable intake and activity levels, where planning directly predicted changes (β = 0.283 for diet; β = 0.139 for physical activity). A 2024 scoping review of 23 interventions, including 15 randomized controlled trials, for adults with long-term conditions reported positive physical activity effects in 7 studies, highlighting the frequent use of action and coping planning (targeted in 22 and 20 interventions, respectively) alongside self-efficacy to improve frequency, duration, and intensity. These findings underscore HAPA's utility in designing targeted, multi-component interventions that prioritize self-regulatory skills for real-world application.^[9]^[14]^[15]

Empirical Support and Recent Studies

The Health Action Process Approach (HAPA) has garnered substantial empirical support through numerous studies demonstrating its efficacy in predicting and facilitating health behavior change across motivational and volitional phases. A comprehensive meta-analysis of 95 studies involving 108 independent samples found small-to-medium effect sizes for key HAPA constructs, with action self-efficacy (r = 0.28) and outcome expectancies (r = 0.22) showing robust associations with intention formation, while coping planning (r = 0.24) and maintenance self-efficacy (r = 0.26) mediated the intention-behavior gap.^[9] These effects were consistent across diverse behaviors, including physical activity and dietary adherence, though past behavior moderated the intention-behavior link, attenuating it by up to 20%. The analysis underscored self-efficacy's pivotal role in both phases, supporting HAPA's theoretical distinction between motivation and volition.^[9] Recent longitudinal and experimental research from 2020 onward has further validated HAPA's applicability in targeted interventions, particularly for chronic conditions. A 2024 scoping review of 23 HAPA-framed physical activity (PA) interventions for adults with long-term conditions, such as type 2 diabetes and cardiovascular disease, revealed that 7 out of 15 randomized controlled trials reported significant PA improvements, with self-efficacy enhancements (targeted in 78% of studies) correlating with better outcomes.^[15] Similarly, a 2024 meta-analysis of 12 randomized controlled trials (n = 1,773 rehabilitation patients) demonstrated that HAPA-based interventions yielded a moderate effect on PA levels (standardized mean difference = 0.43, 95% CI [0.34, 0.53]), with stronger impacts in face-to-face formats and longer durations (>12 weeks), highlighting the role of action planning and goal setting as core behavior change techniques.^[16] Emerging applications extend HAPA to digital and mental health contexts, though results indicate areas for refinement. In a 2024 cross-sectional study of 16,078 sessions on a self-guided digital mental health website, an adapted HAPA model predicted user intention to engage (explaining 83% of variance via perceived need and self-efficacy) but showed limited predictive power for actual engagement levels (1.4% variance explained), suggesting that volitional factors like planning require digital-specific adaptations to bridge the gap.^[17] Overall, these studies affirm HAPA's predictive validity while calling for more rigorous fidelity assessments and integration with emerging technologies to enhance volitional outcomes. As of 2025, additional applications include HAPA-based interventions for oral health in older adults, post-bariatric weight management, and reducing salt intake, with a systematic review confirming its role in non-communicable disease management.^[18]^[19]^[20]

Comparisons and Critiques

Relation to Other Theories

The Health Action Process Approach (HAPA) integrates core elements from several established health behavior theories, creating a hybrid model that addresses both motivational and volitional processes in behavior change. It draws on the Theory of Planned Behavior (TPB) by incorporating intention as a central predictor of action, where attitudes, subjective norms, and perceived behavioral control influence the formation of intentions. However, HAPA extends TPB by introducing a post-intentional volitional phase, emphasizing planning, action control, and coping strategies to bridge the well-documented intention-behavior gap, which TPB largely overlooks.^[13]^[1] HAPA is deeply rooted in Social Cognitive Theory (SCT), particularly through its adoption and expansion of self-efficacy as a key construct. Originating from Albert Bandura's work, self-efficacy in SCT represents an individual's belief in their capacity to execute behaviors necessary for desired outcomes. HAPA refines this by delineating phase-specific forms of self-efficacy—action self-efficacy for initiating behavior, coping self-efficacy for maintenance, and recovery self-efficacy for relapse management—thus providing a more nuanced application within a structured motivational-volitional framework. This integration enhances SCT's focus on reciprocal determinism by adding explicit mechanisms for translating motivation into sustained action.^[13]^[1] In relation to the Transtheoretical Model (TTM), HAPA shares a staged perspective on behavior change, with its pre-intentional motivational phase paralleling TTM's precontemplation, contemplation, and preparation stages, and the post-intentional phase aligning with action and maintenance. Unlike TTM, which relies on stage-matched interventions and processes of change (e.g., consciousness-raising), HAPA prioritizes continuous psychological constructs like self-efficacy and planning over discrete stage transitions, offering greater flexibility for predictive modeling and interventions. Empirical comparisons indicate that process- and stage-based models like HAPA and TTM outperform intention-only models in addressing long-term adherence, though HAPA's emphasis on volition provides stronger explanatory power for the transition from intent to habit.^[13]^[1] HAPA also incorporates aspects of the Health Belief Model (HBM) through its inclusion of risk perception, akin to HBM's perceived susceptibility and severity, which motivate initial engagement with health threats. Yet, HAPA surpasses HBM's focus on threat appraisal and cues to action by integrating outcome expectancies and self-regulatory strategies, resulting in a more comprehensive model that supports both initiation and persistence of behaviors such as physical activity or medication adherence. Recent integrations of HAPA with TPB elements have demonstrated improved predictive validity in contexts like COVID-19 preventive behaviors.^[13]^[21]

Strengths and Limitations

The Health Action Process Approach (HAPA) offers several strengths as a framework for understanding and promoting health behavior change. One key advantage is its distinction between motivational (pre-intentional) and volitional (post-intentional) phases, which addresses the intention-behavior gap prevalent in simpler models by incorporating mechanisms like planning and self-efficacy to facilitate action initiation and maintenance. This phased structure enhances predictive utility, as evidenced by meta-analytic evidence showing small-to-medium effect sizes for core constructs such as action self-efficacy (r = 0.27) and coping planning (r = 0.22) in predicting health behaviors across diverse domains like physical activity and dietary adherence. Additionally, HAPA's flexible, open-architecture design allows researchers to select relevant constructs for specific contexts, making it adaptable for interventions in varied populations and behaviors, from exercise promotion in older adults to medication adherence in chronic illness management. Empirical support is robust, with over 95 studies demonstrating consistent relationships among HAPA variables, underscoring its reliability in both correlational and experimental designs; recent applications as of 2025, including mHealth interventions for physical activity, continue to affirm its validity.^[3]^[22] HAPA also excels in emphasizing self-regulation strategies, such as action planning and coping with barriers, which have been shown to mediate the translation of intentions into sustained behavior, thereby improving intervention outcomes compared to intention-focused theories alone. For instance, interventions grounded in HAPA have yielded significant increases in physical activity levels, with effect sizes indicating moderate improvements in behavior frequency and duration. This focus on volitional factors positions HAPA as a practical tool for designing targeted health promotion programs that go beyond mere motivation to support long-term adherence. Despite these strengths, HAPA has notable limitations. A primary critique is its limited attention to non-conscious processes, such as automatic habits, emotional impulses, or environmental cues, which can influence behavior independently of deliberate cognition and are not explicitly integrated into the model. This omission may reduce its explanatory power in scenarios where subconscious factors dominate, as seen in behaviors driven by temptations or stress rather than planning. Furthermore, while HAPA improves upon the intention-behavior gap, meta-analyses reveal that intentions still only modestly predict actual behavior (r = 0.45), and constructs like risk perceptions exhibit weak effects (r = 0.11), suggesting the model does not fully account for all determinants, particularly past behavior or contextual barriers. The model's complexity, with multiple interconnected constructs, can pose challenges for parsimonious application in resource-limited settings, leading to variability in how subsets of elements are tested or implemented across studies. Recovery self-efficacy, for example, shows inconsistent or small effects (r = 0.18), highlighting potential redundancies or context-specific relevance that require further refinement. Overall, while HAPA provides a solid foundation, its effectiveness may be enhanced by integrating complementary elements from other theories to address these gaps.