In the past, most people exercised every day. They didn't exercise on purpose. Instead, they exercised by working on the land and by walking everywhere. Now, however, people do not take as much exercise. Many people work in offices or factories where they do not have to move around very much. Now that cities are so big, few people walk to work. They drive or travel by bus or train. With modern telecommunications technology, they don't have to move around to get messages delivered. What they have to do is just to press buttons on their phones or other devices.
Because of this unhealthy modern lifestyle, many people try to exercise in other ways. Jogging and running are very popular. Going to the gym is also a popular way of getting exercise. Many women prefer to go to aerobic (有氧的) classes at the gym. In these classes, music is played loudly and an instructor shouts out instructions for the exercises. The people in the class run, stretch and jump around for an hour or more. Men and women also do weight training at the gym. They lift heavy weights to build up their muscles.
Although thousands of people do these sorts of exercises every day, some experts believe that they are actually bad for the body. Running on hard surfaces like roads can damage your feet and knees, and aerobic and weight training can be dangerous if the instructor is not properly trained. It's easy to hurt yourself if you lift heavy weight or exercise hard for a long time.
The experts believe that more gentle forms of exercise are better. They advise people to walk more as it is one of best ways to exercise, and does not damage the body at all. They also suggest traditional Chinese exercises such as Tai Chi because these activities are better for the body than hard, fast activities like running. Tai Chi trains your flexibility and improves your sense of balance. Meanwhile, it has the least harmful effect on your joints and knees.
