The goal of mental fitness is to achieve a healthy mental state through a method that fits each situation, and with clear and specific steps, helps the reader discover where they are, understand how they got there, and what they can do to reach a complete mental well-being. With particular attention to the way in which we feed our mind, the factors that have come to establish certain habits in us, and which often become a block to our intention to improve, are addressed here. With a simple practice, the reader will be able to notice the benefits in his life through small changes in his daily activities. Mental Fitness helps those who practice it to more easily achieve their goals in a faster way, and also leaving them more time to dedicate it to the things that they really enjoy doing, and that are more productive than those that made up their old habits.