Introduction Exercise—you have read about the latest trends in magazines and books, you have studied some of the related anatomical and physiological processes in school, you have watched people competitively engaged in it on television or online, you have probably downloaded an app for it, and at some point, you have done it yourself. It may seem like you are already inundated with daily results from athletic events, information about new workouts and training tips, and reviews of exercise equip- ment and footwear. What, then, can a book like Exercise and Physical Activity: From Health Benefits to Fitness Crazes offer you? Despite the presence of exercise on our screens or on the page, the simple truth is that most of us simply do not do enough of it. According to the Centers for Dis- ease Control and Prevention (CDC), recent data suggests that one in five high school students in the United States do not meet recommended physical activity guidelines, and at least 25 percent of American adults do no physical activity out- side of their regular job. With little or no participation in exercise, millions of us are putting our health at risk for heart disease, high blood pressure, stroke, diabe- tes, certain types of cancer, low bone density, and obesity. We are also more stressed, struggling with depression and anxiety, burdened by poor sleep, and chronically fatigued. These problems, all influenced by inactivity, are associated with an estimated $117 billion annually in health-care costs. Engaging in physical activity is one of the best things you can do for your health, and there are many individuals, public health programs, organizations, and businesses dedicated to helping you become more active. How do you figure out what physical inactivity does to your body? Where can you explore the various activities and sports you might be interested in trying? Which muscles are involved in exercise, and how do you decide on the exercises that will make them stronger? What benefits come with exercise, and what related injuries can you prevent? What career options focus on health, fitness, and exercise? What organizations offer further resources on health, fitness, and exercise if you need them? Exercise and Physical Activity: From Health Benefits to Fitness Crazes answers these ques- tions and more. As an adolescent, I was very much drawn to sports, and I competed in cross- country, volleyball, and track (I dabbled a bit in swimming and cross-country skiing, too). I loved training and sometimes snuck in extra workouts before school. I loved the comradery among my teammates and the work we did together to win.