The aim of this research was to examine if habit strength moderated the influence of attitude, perceived behavioral control(PBC) and anticipated regret(AR) on exercise intention and the influence of intention on exercise behavior in a college student sample, using the extended version of the Theory of Planned Behavior(TPB) augmented by AR. Furthermore, mediation effect and moderated mediation effect were also analyzed. TPB variables and habit strength(SHRI) were assessed at baseline. Exercise behavior was assessed with a validated questionnaire two weeks later. Results showed that the extended model fit the data well: (1)AR had a significant effect on intention over and above TPB, (2)attitude, PBC and AR and the interaction of these variables with habit explained a significant increment of variance in exercise intention, (3) habit and habit*intention interaction explained a significant increment of variance in exercise behavior. The effect of attitude(PBC and AR) on exercise behavior was completely(partially) mediated by intention. The strength of mediation effect decreased along with the levels of habit strength(moderated mediation effect): stronger attitude(PBC, AR)-intention-exercise behavior relations when habit strength was weak. The results of this research suggest that exercise promotion strategy to maintain exercise habit is needed for those who have exercised frequently in the past , whereas exercise promotion strategy to enhance attitude, PBC, anticipated regret and intention is needed for those who have not exercised frequently in the past.