Exertion of self-control produces distinct motivational consequences: the motivation to conserve energy and the motivation to seek rewards. We propose that heightened conservation inhibits reward-seeking, but only when the pursuit of the reward entails substantial energy expenditure. In two studies, we manipulated self-regulatory effort and then had participants engage in an additional task that was either easy or difficult. In Study 1, we found that self-regulatory effort tended to heighten reward-sensitivity but only when the subsequent task was easy. In Study 2, we measured pupil dilation to assess reward sensitivity while participants viewed images of rewarding stimuli. When the need to conserve was intense, we observed reduced pupil dilation for rewards that were energy-requiring but not for those that were energy-giving.