Coaching: The Mental Game - H.A. Dorfman
Peak: Secrets From the New Science of Expertise - Anders Ericsson and Robert Pool
Grit: The Power of Passion and Perseverance - Angela Duckworth (my personal favorite)
The Mindful Athlete: Secrets to Pure Performance - George Mumford
The Organized Mind - Daniel J. Levitin
The Sweet Spot - Christine Carter