Slightly different tone than Joe Barry
A motivator. I believe in it. You don't hit the field for practice, or games, without firing them up. Football is hard. It can hurt, play after play. You learn to love the game, get fired up, and the pain becomes a reward for having done well on every given play.
If you get beat on a play, you don't quit. You just reach further inside, and decide that on the next play, you're going to whip that guy's sorry ass. You're going to whip him so hard he's going to think you're possessed.
The objective is to make the other guy flinch, and when he does, you own the SOB, and you let him know it on every damned play, because you are the master over him, and he's your bitch!
That's what a coach I played for said a long time ago, and when we hit the field, even in practice, we were whipping the hell out of each other on every play, because it's what you do in practice that carries over to the field.
I know that what I said sounds harsh, but football is not a "contact sport." It's a collision sport, and it's violent. Basketball is a contact sport. You either embrace the pain, or go play something other than football, because you're taking up a pair of shoulder pads that belong on someone else, who will give that extra measure.