The Köhler effect is an increase in task motivation that occurs in performance groups when one is (a) less capable than one’s fellow group members, and (b) one’s efforts are particularly indispensible for group success. Recently, it has been shown that the Köhler effect can dramatically increase one’s motivation to exercise. The present study examines the potential moderating effect of the provision of extrinsic incentives on such Köhler motivation gains. When participants were offered such an extrinsic incentive for persisting at an exercise task, a robust Köhler effect was observed—participants who thought they were the less capable member of a dyad working at a conjunctive-group exercise task persisted 26% longer than comparable individual exercisers. But an even stronger effect (a 43% improvement) was observed when no such incentive was on offer. Possible explanations and boundary conditions for this moderating effect are discussed.