According to the ancient Chinese discipline of chi kung (pronounced chee gung), the body's energy is released by the air breathed into it. Zi, a classically trained American singer raised in China, has adapted that idea in an intriguing method she calls chi yi. (Chi means breath, breathing or air.) Her premise is that controlled breathing can create new sources of life-enhancing energy. In six concise, uncomplicated lessons she shows how to tap into that energy through a range of exercises (accompanied by line drawings), imagery and situational applications. Her techniques for using the body's inner dynamics (the Chinese "core") will be especially valuable in relieving stress, building stamina and engaging in sports.