Because a known fact is better than an unknown fact.
If you want to be Mark Spitz then go for it. If you want to be Michael Phelps then you'll have to work for it. Nobody should wake up to a lower expectation of themselves.
If you're fail to prepare, you're prepared to fail.
Life is everchanging, if you cease to change, you cease to live.
Past performance speaks a tremendous amount about one's ability and likelihood for success.
I'm trying to do the best I can. I'm not concerned with tomorrow, but with what goes on today.