The present study investigated implicit processes associated with pain and tested the idea that priming pain during task performance systematically influences effort mobilization—i.e., motivational intensity. Primed pain was predicted to increase perceived task difficulty and in turn effort mobilization but only when success was justified by a high incentive. Effort-related cardiovascular reactivity was assessed during a habituation period and a difficult short-term memory task presenting pain-related or neutral words together with a moderate or high incentive for success. Results fully supported the predictions. Cardiovascular reactivity was especially strong in the pain-prime/high-incentive condition compared to the other three conditions. Moreover, participants felt less capable to perform the task in the pain-prime than in the neutral-prime condition. Participants made also more errors during the task in the painprime condition than in the neutral-prime condition. These findings show that implicit pain has a systematic influence on effort mobilization and a similar detrimental effect on task performance as physical pain. Implications for other effortful processes associated with selfregulation and pain condition are discussed.