I listened to the audio version of this book which is read by the author. It was great.
I have been using self help books for years, some great, some so-so. This book ranks among the best of any of them. It is cross between David Burn's "Feeling Good" (a classic you will find on most psychologist's book shelves) and Byron Katie's "The Work" to which the author refers.
The book comes with a worksheet which you work through numerous times through the book. I have completed over 20 of these now and I am sleeping better and am more relaxed and stress free than I have been for many years. All within a couple of weeks. You will get out of this book what you willing to put in.