Making choices, responding actively instead of passively, restraining impul
ses, and other acts of self-control and volition all draw on a common resou
rce that is limited and renewable, akin to strength or energy. After an act
of choice or self-control, the sell's resources have been expended, produc
ing the condition of ego depletion. In this state, the self is less able to
function effectively, such as by regulating itself or exerting volition. E
ffects of ego depletion appear to reflect an effort to conserve remaining r
esources rather than full exhaustion, although in principle full exhaustion
is possible. This versatile but limited resource is crucial to the self's
optimal functioning, and the pervasive need to conserve it may result in th
e commonly heavy reliance on habit, routine, and automatic processes.