" The player of the inner game comes to value the art of relaxed concentration above all other skills; he discovers a true basis for self-confidence; and he learns that the secret to winning any game lies in not trying too hard. He aims at the kind of spontaneous performance which occurs only when the mind is calm and seems at one with the body, which finds its own surprising ways to surpass its own limits again and again. Moreover, while overcoming the common hang-ups of competition, the player of the inner game uncovers a will to win which unlocks all his energy and which is never discouraged by losing. "

― W. Timothy Gallwey , The Inner Game of Tennis: The Classic Guide to the Mental Side of Peak Performance