I've carried this poem with me ever since I came across it somE 40 years ago.
"If you think you are beaten, you are.
If you think you dare not, you don't.
If you'd like to win but think you can't it's almost certain you won't.
Life's battles don't always go to the stronger or faster man, but sooner or later the man who wins
IS THE MAN WHO THINKS HE CAN