Exerting self-control leads to a diminished capacity to carry out successive acts of self-control, a process termed ego depletion. The present study investigated whether dispositional optimism, priming of an optimistic orientation, or their interaction can counteract the ego depletion effect. A total of 160 participants performed a self-control-demanding weight-lifting task on two occasions. Half of the participants were depleted between the two weight-lifting tasks. Because depletion of self-regulatory resources can undermine optimism half of the participants in the depletion, and no-depletion condition were primed for an optimistic orientation before performing the second self-control task. Results demonstrated an interaction between dispositional optimism and optimism priming. Only in participants high in dispositional optimism did the optimism prime lead to undiminished persistence on the weight-lifting task. These results demonstrate that dispositional optimism may lead to improved goal persistence in the face of adversity only under conditions in which optimistic schemas are activated.