YOU ARE WHAT YOU THINK. This is one of my favorite positive thinking quotes:

If you think you are beaten you are;
If you think you dare not, you don't;
If you want to win but think you can't;
It's almost a cinch you won't.

If you think you'll lose you're lost;
For out of the world we find
Success begins with a fellow's will;
It's all in a state of mind.

Life's battles don't always go
To the stronger and faster man,
But sooner or later the man who wins
Is the man who thinks He can.

That is my favorite positive thinking, how about you?