I am an instructor for a gentle yoga class. We are using the Miracle Ball during our final relaxation. Those clients with back issues swear by the ball. One client travels extensively and he carries the balls in his luggage for use at the hotel. He informs me that his back is now virtually pain free. Other clients who spend a lot of their day driving also love the Miracle Ball. I highly recommend the Miracle Ball to anyone who may have back issues. The book is useful when starting out but one can quicly modify and adapt to ones own body needs.