Constant self-control leads to physical and mental exhaustion. By suppressing feelings, the body expends extra energy and thereafter reduces concentration on difficult tasks.
However, this (volitional) state of exhaustion through self-discipline is not necessarily sustainable, but can serve to strengthen the will once the fatigue has been overcome.
The positive effect of this ego control is similar to the sustained increase in performance of a muscle that has been temporarily exhausted through training. According to the authors, however, the model does not take into account that a moderate form of self-control does not lead to exhaustion, but – quite the opposite – has an energizing effect.