It’s actually just a part of a longer poem about tennis, but it captures what I think about when I do yoga, and probably what a lot of people think about when they do their sports of choice, too.
From “Tennis,” by Robert Pinsky (full poem here):
Your body, you will conquer your fatigue.
By understanding your desire to win
And all your other desires, you will conquer
Discouragement. And you will conquer distraction
By understanding the world, and all its parts.