Usually in the evening 19:30-20:30 this time for the best time period for exercise, for the following reasons: First, this time according to emergency epidemiological statistics, is the lowest rate of sudden cardiovascular and cerebrovascular death, exercise in this time period, when the amount of exercise is slightly excessive and will not cause excessive or excess burden on the body’s cardiovascular and cerebrovascular, relative exercise is relatively safe. Secondly, this time is the air index is relatively fresh time, so it is a time for non-plants to photosynthesis, will not release a large amount of carbon dioxide in the air, exercise air index is better. Third, this is the time when the body’s basal metabolic rate is low, this time more exercise can increase the body’s metabolic processing, effective for weight loss and fat loss.