Being empathetic about self-control reduces our own willpower

ScienceDaily - You Wear Me Out: Thinking Of Others Causes Lapses In Our Self-control

Previous work in the exercise of will-power and self-control has shown that it depletes when used, impairing subsequent exercises in self-control. This experiment asked participants to imagine they were someone who had to exercise self-control, e.g. a hungry waiter surrounded by a lot of delicious food that he couldn't eat. Participants were then asked how much they'd spend on a series of luxury items, and others were asked to perform memory tasks or word games. Those who were asked to imagine the waiter's hunger were more likely to pay more for the luxury items and performed worse on the follow-up tasks than the controls. The theory was that imagining using self-control left the subjects in a mentally weakened state, especially regarding their capacity to exercise their own self-control.