ObjectivesTo test whether affective response to an acute bout of exercise can predict regular voluntary exercise, and specifically whether a positive affective response helps translate intentions into behaviour.DesignA prospective correlational design.MethodsParticipants (N=127) recruited from the community reported intentions to engage in voluntary exercise and frequency of participation in voluntary exercise both at baseline and at a 3‐month follow‐up. Self‐reported positive affect, negative affect, tranquillity, and fatigue were assessed during a bout of moderate intensity exercise.ResultsWithin subject slopes for increases in positive affect and decreases in fatigue during exercise, and increased tranquillity and decreased fatigue post‐exercise were associated with more frequent participation in exercise at follow‐up. Changes in negative affect did not predict exercise at follow‐up; however, this was likely due to floor effects leading to lack of baseline variability in negative affect. Importantly, a positive affective response to exercise moderated the intention–behaviour relationship, such that those who responded to exercise more favourably exhibited stronger relationships between intentions and future exercise behaviourConclusionsWe conclude that exercise‐related increases in positive affect and tranquillity and decreases in feelings of fatigue can aid in the successful translation of exercise intentions