["Applied Psychology: Health and Well-Being, Volume 18, Issue 3, June 2026. ", "\nAbstract\nThis study examined whether a four‐week mindful exercise intervention could enhance affective responses and promote exercise intention and behavior. We also tested whether affective valence during exercise and post‐exercise enjoyment predicted these outcomes. Ninety‐seven insufficiently active adults in the intention or preparation stage of exercise behavior were randomly assigned to mindfulness, distraction, or control conditions. Participants engaged in low‐ to moderate‐intensity exercise two to three times per week for four weeks while receiving a guided mindfulness audio, a neutral podcast, or no audio, respectively. Affective valence, post‐exercise enjoyment, exercise intention, and exercise behavior were assessed at baseline, post‐intervention, and one‐month follow‐up. Linear mixed‐effects models showed that mindfulness was associated with higher affective valence than distraction and control, and higher enjoyment and exercise intention than distraction, with smaller or nonsignificant differences relative to control. Exercise behavior increased at post‐intervention and declined at follow‐up, while remaining above baseline. Mediation analyses indicated that post‐exercise enjoyment, but not affective valence, significantly mediated the intervention's effect on exercise intention. Findings suggest that mindfulness during exercise enhances affective experiences and exercise intention, which may support engagement in physical activity. However, behavior changes were not sustained at follow‐up, underscoring the need for strategies that maintain long‐term effects.\n"]