I went to the gym the other day and signed up. Is it because I have been exercising for a long time? If you insist on going to the gym every day, your arms will get thicker? Will real people grow up? Do you have friends who know about fitness? The increase of muscle tolerance in all parts of your body will naturally make you impregnable. As for the big ones, I can only say that exercise contributes to the growth of height. Don't do weight-bearing squats. In addition, the process of muscle gain is very painful. You even have to like the pain, and the nutrition after exercise should be in place, otherwise it will be equivalent to wasting more than half of your efforts.