My trainer has a way of pushing me through sheer exhaustion, for completing those last few reps, when my energy tank is running on empty. The key is to push hard, and then some, because the sense of accomplishment when the workout is done is incredible.
Probably a key lesson here for business, and life. One must learn to dig deep, when the chips are down, and make success a habit. Unfortunately, quitting is a habit too. Bad habits are easier than the good ones.
Remember — “Pain is temporary, quitting is forever.”