I can't think of any quote atm; I do have a few though.
I usually just think about the day before something needs to be completed. I always regret all the time I spent doing nothing. I know all the hard work will pay off later on, and even then, I'll wish I could've done more.
That's what gets me going. Thinking about getting it over with in a way I'm confidant and proud of. Nothing is more satisfying than the feeling of earned success. Self-brought-on failure is the worst.
Of course, this is easier said than done. I still have issues getting the ball rolling, sometimes. :}