A warning beforehand - this book covers much the same ground as his earlier book, 'Beyond Happiness'. This one is slightly more practical, whereas the other is more philosophical, but essentially they cover the same ground. I wouldn't recommend buying both, unless the cost of the books is irrelevant to you. Both are good, and which you prefer will probably depend on whether you like a lot of repetition of the philosophy, or a lot of repetition of the practical exercises. Having read 'Beyond Happiness' first, I bought this expecting an expansion of the ideas, but didn't really learn anything new. Some pages are copied directly.
Having said that, it's (or at least, one of them) is still a worthwhile read. I don't agree with all of the philosophy (explained at greater length in Beyond Happiness), but it is still thought provoking. It comes across as slightly more airy-fairy in this book, as he goes into less detail, but the "Quantum Entrainment" exercises (which is essentially a simplified form of meditation, nothing more) are very calming.
A good book and good technique for calming your thoughts. If you've tried meditation and cannot clear your mind of thoughts, you may find this variant useful (basically he just gives you suggestions for how to notice the gaps between your thoughts. Simple but effective.).
Second warning: the techniques are deceptively simple. You may end up thinking you've been ripped off if you want something complicated enough to justify the book price. I almost feel like describing the techniques here, but it would take a few paragraphs - and you can pick up a lot of it by visiting the author's Quantum Entrainment webiste, where they discuss the techniques for free :) - The book itself is still worth a read I think.