How to prevent life-threatening diseases by reducing or eliminating those causes that are within each person's control. The subject certainly isn't new. (Several books on preventing major diseases have been published recently: Prevention, The New Medicine; Heartplan). Neither is the nutrition message, one that most doctors seem to agree on at this point: a high-fiber, high-carbohydrate diet, low in fat, sodium, sugar, alcohol and coffee; no smoking. Enough of the right kind of exercise, and stress-reducing attitudes and lifestyles complete the preventive medicine prescription. But for the sake of good health, the more the merrier, especially when the message is presented in an understandable, easy-to-use format. Each major disease and health risk is explained fully and the connection made between the risk factors and the disease. The thoughtful, thorough self-evaluation quizzes in every section are compelling invitations to participate in toting up health risks and to take an active role in correcting them. The nutrition and exercise plans, which are the keys to reducing the health risks, are equally thorough, easy to digest and offer some unique, practical ways to custom tailor safe, sane weight-loss and exercise programs to fit individual needs. A sound personal guide, but nothing new.