According to a new report from a university, we know most of the world's teens don't get enough exercise every day. Activity standards（标准） are different in different countries, for example, there are more boys who don't get enough exercise than the girls.
Why don't teens go out for exercise? One main reason is that they always have technology products in their hands or around them. They spend too much time on smartphones, computers and TVs in their free time. Many teens find it very hard to pull themselves away from these devices（设备）. The report says that young people need to do less in the digital（数码的）, but more in the real world. It advises kids to get at least an hour of exercise every day. This could include running, biking
More and more research shows that exercise not only helps the body but also helps the brain. Besides, doing sports helps kids to make friends. Mark, a sports fan, but now he has become taller and stronger. And he has made lots of friends with the same interest.
