The main time periods when it is not advisable to exercise include after eating, when you are in a poor mood or before going to bed. 1. After eating, more blood flow is needed to the gastrointestinal tract to help digest and absorb nutrients; exercising at this time will affect the normal digestion of food and impair gastrointestinal function. 2. Low mood will affect the normal physiological response when exercising, such as low mood causing lack of mental concentration and easy accidental injury during exercise. 3. Exercise before going to bed will cause excessive excitement of the nervous system, but will cause insomnia and other symptoms; and then affect the body’s normal metabolism. Appropriate exercise time is generally around 9:00 in the morning or between 4:00 and 5:00 in the afternoon, and to take a scientific approach to exercise, and must be moderate exercise to avoid fatigue, sports injuries and so on. In addition, if you have the habit of exercising in the morning, it is recommended to eat and drink a small amount of water before exercise to avoid hypoglycemia, acute cardiovascular disease and other accidents that occur when exercising on an empty stomach.