How Mindfulness During Exercise Shapes Affective Experience: A Preliminary Study of Dynamic Momentary Psychological Mechanisms

Objectives Mindfulness-based exercise has been shown to enhance affective responses to exercise, yet the momentary psychological mechanisms underlying these effects remain poorly understood. The present study examined how mindfulness during exercise shapes affective experience by focusing on dynamic, momentary psychological processes across a four-week intervention. Methods Physically inactive college students were randomly assigned to a mindfulness-based exercise condition, a distraction condition, or a control condition and completed 2–3 supervised exercise sessions per week for four weeks. Using an ecological momentary assessment (EMA)–informed design, immediate post-exercise affect and mindfulness-related psychological processes were assessed following each exercise session. Multilevel models decomposed within-person and between-person effects to examine concurrent associations between psychological processes and affect, moderation by intervention condition, and exploratory lagged effects across sessions. Results Session-specific fluctuations in acceptance, nonreaction, attention–awareness, and decentering were all positively associated with immediate post-exercise affect at the within-person level. Moderation analyses indicated that mindfulness-based exercise selectively strengthened the momentary association between nonreaction and affect, whereas other mechanisms showed comparable associations across conditions. Exploratory lagged analyses revealed no evidence that prior-session levels of acceptance or nonreaction predicted affective responses at subsequent sessions beyond concurrent effects. Conclusions These findings suggest that mindfulness influences affective experience during exercise primarily through dynamic, momentary psychological processes rather than sustained carry-over effects. By highlighting nonreactive engagement with internal experience as a key mechanism, the present study advances a process-based understanding of how mindfulness operates in exercise contexts and underscores the value of EMA approaches for capturing dynamic affective mechanisms.