Book by Ted Williams, the greatest hitter who ever lived, on the thing he dominated more than anyone before or since. Williams was also one of the greatest, if not the greatest, hitting coaches ever. Baseball people will enjoy it because it's a well written treatise on the subject, and there are a lot of cool anecdotes and stories.
Non baseball people may enjoy the other aspects about how to be elite/successful at a chosen sport:
1. Be obsessed, seriously obsessed, both with what you're doing and what your opponent is doing. Tony Gwynn on Williams-- "He is one of a kind,'' Gwynn said. "His memory was unbelievable. He could dig in to his memory bank, and pull out all sorts of stuff. All good hitters have that, but he had it to a higher level than anyone I've ever met. It was uncanny the stuff he could pull out. He knew the pitcher, the weather, the way the ball was carrying that day, the thickness of the grass.''
2. Understand your strengths and limitations, do the things that work for you, your style, and your body
3. When coaching keep things simple, when coaching high level athletes, it's the little things that matter
4. Keep distractions you can control to a minimum. Even things like a poorly fitting uniform were unacceptable to Teddy Ballgame.
5. Work within the limitations of what your opponents give you.
6. KISS, focus on the basics
7. Work your ass off
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