An interesting idea. Roy Baumeister of Florida State University seems to conclude that the "mental energy" (my term for it, not his) needed for conscious and deliberate behavior is the same phenomenon as an athlete who has to pace themselves so they don't burn through their physical reserves too fast to compete effectively. Like the athlete a person's self-control energy can become depleted just like a runner's glucose or oxygen levels. If Baumeister turns out to be correct his findings sure do explain a lot about how people act.
