- A book based on 7 principles. Each is simple and is confirmed by numerous psychological and scientific studies. For information, its author worked on the course of happiness of the Harvard University with Dr. Tal Ben-Shahar. - When flying over this book, one can not help thinking "yet one more psychology book". Deepening it, we see that each of the 7 principles are complementary, we learn a lot about our psychological functioning and especially the author gives many simple and effective tools to change gently but deeply and become optimistic. For information, optimism makes first happy but also more efficient and intelligent. - If you really want to change your habits, teach your brain to look for what is rather than what's wrong, regain self-control and other essential objectives, this book is perfect. - By buying this book, I discovered a pearl. - I also wish you to read and apply this book.