After swimming or taking a bath, doing chest and back rubbing exercises with a dry towel can prevent cancer. The scientific principle is that there is a type of tissue cell under the human spine that is usually in a dormant state. After being stimulated to become active, it enters the bloodstream and forms reticular cells, which can enhance the body's immune capacity and achieve the purpose of fitness and cancer prevention. Chinese medical experts have found that after entering puberty, the mammary glands develop and the thymus glands atrophy. The thymus is the central organ of the human immune system, and the hormones it secretes are important substances for the human body to resist diseases and prevent cancer. Therefore, using the method of rubbing the chest to stimulate the recovery and improvement of thymus function can help enhance the body's anti-cancer ability. The method of rubbing the chest and back is very simple and easy to perform. It can be done after getting up in the morning and before going to bed at night. Just use a dry towel to rub the chest and back up and down and left and right until the skin turns red and warm.