A、Because of their love for hobbies and pastimes. B、Because of their strong desire for good health. C、Because of their passion f

In recent years, many Americans of various ages have become interested in improving their bodies. They have become  devoted to physical fitness. Exercise has almost become compulsive with many persons who have a strong desire to be more physically fit.     By nature, Americans are enthusiastic and energetic about their hobbies and pastimes. They apply their passion and energy to running or jogging. As a result, there are running clubs to join and many books and magazines to read about  running.
    The desire to be physically fit is explained by a "passion" for good health. The high rate of heart attacks in the 1960s caused an increase on the part of the public in improving the human body.
    Middle-aged people especially suffer from heart attacks. Thus, they are one group strongly interested in more physical exercise. In fact, many doctors encourage their patients to become more physically active, especially those who are accustomed to sitting or to taking little exercise. It is interesting to note that the rate of heart attacks began to decline in the 1970s and it is still decreasing. Physical fitness currently enjoys a favored role in the United States. It is a new "love" that many Americans have cherished. Will it last long? Only time can tell--or until another "new passion"  comes along.’?