I remember reading the poem below (or one very similar) about 55 years ago in a Sunday School class.
I've since seen it in a couple of different versions.
One is titled, "If You Think You're Beaten," and I've also seen a similar version titled "You Can If You Think You Can."
And I've seen it with the title of "The Man Who Thinks He Can."
Either way it is a pretty good message.
In a Bible Version called Good News for Modern Man, or The Good News Bible (GNB)
and more recently called Today's English Version (TEV),
Proverbs 4:23 says, "Be careful how you think; your life is shaped by your thoughts."
I think it was Billy Graham who called the Book of Proverbs, "heavenly wisdom for earthly living."
If You Think You're Beaten
If you think you're 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 for sure, you won't.
If you think you're losing, you've lost.
For out in the world we find -
Success begins with a person's will,
It's all in the state of mind.
If you think you're outclassed, you are,
You've got to think high to rise.
You have to stay with it,
In order to win the prize.
Life's battles don't always go,
To the one with the better plan.
For more often than not, you will win,
If only you think you can.