The Inner Game of Tennis by Timothy Gallwey was an interesting read that I heard of from an article by Chris Ballard for Sports Illustrated titled "The little-known book that shaped the minds of Steve Kerr and Pete Carroll."
Gallwey's book is subtitled The Classic Guide to the Mental Side of Peak Performance and in it, he writes of how "every game is composed of two parts, an outer game and inner game, that which takes place in the mind of the player, and is played against such obstacles as lapses in concentration, nervousness, self-doubt, and self-condemnation."
This inner game is written of by Gallwey as being one that can easily hurt us, with our "telling self" judging results, and distracting from our "doing self" completing activities. In terms of simply doing, Gallwey writes of how if we focus on having a clear picture of what we want to accomplish and then just act, we'll likely be happier when all said and done. This clear picture can be formed by observation, of both others and ourselves, with a non-judgmental awareness of our movements.
It's a short book from Gallwey and one with some compelling ideas.