If you think you are beaten, you are

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.

                                         -Walter D. Wintle