I read a book called “The Goal” by Goldratt and he describes his theory of constraints. One of the main predictions of his theory is that the existence of many resources working at maximum capacity is symptomatic of a wildly inefficient production system. Thus you shouldn’t feel guilty about not giving 100% every day. This behavior is necessary to properly balance the total throughout of your company. Ideally only one person should be giving 100% in any given company, and in a fair and balanced system this would be the CEO who is concomitantly receiving massive compensation.