Georges St-Pierre on training on the days you don't want to

Georges St-Pierre holds to the theory that he gets better not on days that he wants to go to train, is motivated and exciting and feeling good about going to the gym; rather he feels that he gets the most improvement from days where he doesn't want to go, can't stand going, but overcomes that blanketing negative aura and energy within him and musters up the will-power to get up and give his all in training. GSP mentions this in his book The Way of the Fight:

...if you can overcome the negative energy coming from your tired body or unmotivated mind, you will grow and become better. It won’t be the best workout you have, you won’t accomplish as much as what you usually do when you actually feel good, but that doesn’t matter. Growth is a long-term game, and the crappy days are more important. The best part is at the end of your workout on the crappy day. You feel better about yourself, happier and proud.