It is usually recommended that aerobic exercise at 19:30-20:30 pm is the best for the following reasons: First, epidemiological surveys have shown that the incidence of myocardial infarction and cerebral infarction in patients who go to the emergency room is usually lowest in the period from 19:00-21:00 pm, so that exercise at this time does not have a great impact on cardiovascular and cerebrovascular loads. Secondly, when aerobic exercise is carried out during this time, the photosynthesis of plants is usually finished, and they will not release excess and excessive carbon dioxide into the air, so the oxygen content in the air is higher. Third, this is the time when the body’s metabolic rate is at its lowest, so exercising at this time will increase the metabolic rate, which is good for weight loss. Fourth, this time period from the evening sleep and about three hours, this time to exercise to play the role of blood at the same time also help to sleep.