To put it bluntly, the process of fitness is to improve your physical fitness and make your physical fitness have stronger physical strength and energy to do what you want to do. This method of improving physical strength is long-term, not to say crazy exercise within a month, and then gain muscle. In this case, you exercise. This is not true. This is for simple muscle gain, not for fitness, but for improving physical fitness and prolonging life. Exercise is mainly moderate, that is, stick to appropriate activities for about an hour every day, and then stick to it for three to five years. You will find that your constitution has undergone a qualitative change. You may feel breathless after running a kilometer, but after three to five years of fitness, you will find that running a kilometer is not a problem at all.