Although Mr. Lewis is knowledgeable and sincere enough, he seems to get lost in his own Taoistic/Gurdjieffian philosophizing about breathing and being. He tries to put too much into this book and the result is academic, rather than useful. Strip away all the excess philosophy, and what is left is an over-condensed rehash, mostly, of the first level of Mantak Chia's Healing Tao work, with some experiential Gurdjieff work mixed in.
I suggest skipping this book and going straight to the source: Chia's inner smile and healing sounds practice is excellent and clearly and thoroughly presented in Transform Stress into Vitality. The inner relaxation gained from this specific practice alone will probably soften and deepen your breathing noticeably.
But then, move to Frantzis's Open the Energy Gates of Your Body (recent newly revised edition). The new edition contains a beginning presentation of Taoist "Longevity" breathing which is excellent, pedagogically sound, b.s.-free, and safe when directions are followed precisely, in the order presented. Although Lewis understands and talks about opening space in the body for healthy breathing, Frantzis' presentation is far more useful and direct.
This is my first exposure to breathing work. This book guides you through the basics of it so you can understand its principles and the tremendous power of self-sensing and breath. I am profoundly impressed with what I am learning about myself and recommend it to anyone new to the subject.