Financial incentives have shown strong positive short-run effects for problematic health behaviors that likely stem from time inconsistency. However, the effects often disappear once incentive programs end. This paper analyzes the results of a large-scale workplace field experiment to examine whether self-funded commitment contracts can improve the long-run effects of an incentive program. A four-week incentive program targeting use of the company gym generated only small lasting effects on behavior. Those that also offered a commitment contract at the end of the program, however, showed demand for commitment and significant long-run changes, detectable even several years after the incentive ended. (JEL D03, I10, J32)