This is the first fitness book that explains and organizes behavior analytic training (or "BAT") principles in a systematic user friendly manner that the reader can apply to gain and maintain fitness, health, and lose weight. Part one lays out the rationale for improved fitness, and details how being fit enables living a more value filled, meaningful and happy life. In addition to many physical benefits, increased fitness results in reduced anxiety, depression and has many other psychological benefits. In part two, the nuts and bolts of BAT are presented; how to measure, assess, and gradually, effectively and beneficially change fitness, weight and health related behaviors; how to make and use meaningful, realistic and effective short-term, intermediate and long-term goals. You are also taught how to accept and handle, in a productive manner, any discomfort exercise may produce. Part Three covers further considerations and advanced issues including the nature of the "self" as it relates to fitness; breaking bad habits; how to graph behavior and use graphs to assist health related behavior change; how to learn to relax and use relaxation; and the scientifically proven, most effective procedures for effective, lasting and healthy dieting, weight loss and weight loss maintenance.