Previous studies have found that acts of self-control like emotion regulation deplete blood glucose levels. The present experiment investigates the hypothesis that the extent to which people’s blood glucose levels decline during emotion regulation attempts is influenced by whether they believe themselves to be good or poor at emotion control. We found that although good and poor emotion regulators were equally able to achieve positive and negative moods, the blood glucose of poor emotion regulators was reduced after performing an affect-improving task, whereas the blood glucose of good emotion regulators remained unchanged. As evidence suggests that glucose is a limited energy resource upon which self-control relies, the implication is that good emotion regulators are able to achieve the same positive mood with less cost to their self-regulatory resource. Thus, depletion may not be an inevitable consequence of engaging in emotion regulation.