All climbers need flexibility. And balance, both mental and the more obvious physical versions.
Yoga is one of the best disciplines for developing these skills. Unfortunately Yoga books are often written for people who want to study Yoga. The Athlete's Guide to Yoga is different. Written by a qualified cycling and triathlon coach it focuses on practices and poses which benefit the athlete, whether for training or warm-up/down. The emphasis is very much on the simple practical aspects, both in performance and benefits; the philosophical and esoteric aspects of Yoga are mentioned in passing.
The instructions are delivered by lucidly written text and clear, posed photographs. Throughout the book emphasis is placed on working with your own body to avoid injury and gain the greatest benefit.