Bone Games: Extreme Sports, Shamanism, Zen, and the Search for Transcendence 
Rob Schultheis

This one is a pretty deep cut in the world of endurance literature. The premise is that extreme sports (mountaineering, ultra endurance events, etc) are a modern, western, form of vision quests. An attempt by domesticated, bored, largely affluent, westerners to reconnect with something dangerous and life affirming.

This isn’t a new idea, but Schultheis ties these ideas to his own story in an engaging, and at times inspiring, way. Perhaps not the greatest book ever written about the spiritual aspects of sport, but still deeply enjoyable for those interested in this area.

Recommended for the enthusiast.