Although most U.S. adults have initiated an exercise program at some time, only a fraction are able to maintain consistent exercise. Instead, research suggests that intermittent exercise is commonplace among U.S. adults, underscoring the importance of identifying factors associated with consistent exercise at a level that promotes health and long-term maintenance of this activity. We proposed a theoretical model in which mindfulness and acceptance may promote exercise initiation and maintenance. Mindfulness, acceptance, and suppression were examined as a function of exercise status in 266 YMCA exercisers. Those who were successful at maintaining exercise tended to score higher on measures of mindfulness and acceptance, and lower on measures of suppression. Findings are discussed in light of our proposed theoretical model in which exercisers having greater mindfulness and acceptance are less reactive; responding with more balanced appraisals to threats to their exercise regimen which in turn promotes increased exercise maintenance. Future studies should utilize longitudinal design to examine causal relationships between variables.