It's different for everyone. The word motivation can be motivational or just infer on form of some other word that makes you tick. Words like Awake and Arise have been known to stand out.
I wouldn't really say a single word is motivational. I can't see someone hearing goal or another word and being motivated by it. I would say it'd more have to be a phrase/quote. "Don't watch the clock; do what it does. Keep going."