I don't take part in fitness programs except heavy muscle training (I have no money). I swim, run and play ball, and the amount of exercise far exceeds that of ordinary people. I also have sports injuries, such as tennis elbow and ankle ligament tears several times, and my knee hurts slightly. As long as I exercise, some injuries are easy for me, but at my age, I will know that I can save a ball in front of the net without diving or splitting, so that the other side can get this point. When running, I don't pay attention to the speed of a few seconds. I pay more attention to my goal of running smoothly, evenly and without fatigue ... these are things that I began to pay attention to when I was near middle age. It is very important to do my best. You must have a coach or a fitness partner for muscle strength training, otherwise you will be in big trouble once something goes wrong. I've seen too many such classes in the gym before. I suggest finding a reliable coach or fitness partner!