We propose that egotism about one's abilities may be related to good self-regulation and a lack of self-control may reduce estimations of aptitudes. Self-control depletion should lead to more accurate and therefore less lofty predictions of future performances. In two experiments, self-control depletion was manipulated by having participants either resist tempting cookies or by inhibiting thoughts about a white bear. In both cases, nondepleted participants made bolder predictions about their future performance on a video game than their depleted counterparts. Instead, depleted participants were more modest in their predictions and more accurate in their predictions than nondepleted participants. These findings suggest that depletion undermines self-assurance in oneself, which may have implications for theories of depressive realism, accuracy, confidence, and goal setting.