Our bodies still have a certain mechanism when they exercise. Running is a movement in which the muscles and tissues of the whole body coordinate, and the respiratory system and blood circulation system cooperate. Under normal circumstances, the reason why you can't insist on long-distance running is nothing more than a violent heartbeat and deeper breathing. Simply put, I can't breathe, I still have a breath, my stomach is uncomfortable, and my knees and feet hurt. If it is not physical discomfort, these can be overcome. Both the respiratory system and the cardiopulmonary system can be improved by regular exercise. When we persist in exercise for a long time, our cardiac output will also be improved, and the maximum heart rate will be reduced to some extent during exercise. Many professional athletes have a slow heartbeat. Body muscle tissue will also enhance its function according to the "experience" accumulated in continuous exercise, making it stronger and better protecting bones and joints.