From Intention to Enactment: Action Planning and Habit Automaticity Distinguish Successful from Unsuccessful Intenders to Engage in Regular Leisure-Time Moderate-to-Vigorous Physical Activity

University students often intend to exercise regularly but fail to translate intention into action. The present study tested which post-intentional processes distinguish successful from unsuccessful intenders in self-reported regular leisure-time moderate-to-vigorous physical activity (MVPA) enactment. Chinese undergraduates from 10 universities completed a three-wave survey administered at roughly two-week intervals. Habit automaticity was assessed at Wave 1, intention together with action planning and coping planning at Wave 2, and self-reported regular-exercise status at Wave 3. Because the dependent variable was assessed using a single stage-based self-report item, the findings should be interpreted as explaining self-reported regular-exercise status rather than objectively measured MVPA volume, frequency, or intensity. Primary analyses focused on students classified as intenders under the prespecified threshold (n = 1119 of N = 1670) and used hierarchical logistic regression to predict Wave 3 active versus inactive status. Under the primary threshold, 43.23% of participants were successful intenders and 23.77% were unsuccessful intenders, yielding an intention-behavior gap of 35.48% among intenders. Confirmatory factor analyses supported treating action planning and coping planning as distinct constructs. Among intenders, stronger action planning, stronger habit automaticity, and stronger intention strength independently predicted greater odds of meeting the regular-exercise criterion at follow-up. Coping planning did not show unique predictive value once action planning, habit automaticity, and intention strength were considered simultaneously, and no planning × habit interaction was supported. The pattern was robust across three alternative intention thresholds. These findings suggest that, among already motivated university students, successful exercise enactment depends less on coping planning alone than on a combination of commitment, concrete scheduling, and emerging behavioral automaticity. Interventions for student physical activity may therefore benefit from emphasizing detailed action planning and repeated performance in stable contexts.