Without something bigger than yourself to work for, then all of your work energy is actually fueled by one of the other six deadly sins. You may work exceptionally hard because of envy to get ahead of somebody, or because of pride to prove yourself, or because of greed or even gluttony for pleasure. In short, acedia is the most subtle idolatry of all. It puts the cynical self at the center of your life. And when you do that you release all the worst vices and sins to be the main animating energies behind your work.