My main five (sorry, I just had to vote for my own submission (441); DQ that vote if you must):
441. Surprise yourself.
436. It doesn't have to be fun to be fun.
376. Your body will thank you . . . later.
215. I'd rather be stronger than I look
40. Beyond the fitness routine. Beyond routine fitness.
Only slightly off-color:
5. Crossfit is my daddy