The Mind Gym by the Mind Gym
This great book is full of brilliant and highly usefui psychological suggestions and tips about improving the quality of your life.
What makes this book different to most of the books out there is that it takes from quite a lot of psychological research which is all presented in a highly understandable way and it's packed full with things to do to improve how you use your brain.
Covering a wide variety of areas in your life, the mind gym is sometghing special in the personal development field. Highly recommended.