Theoretically, 40 minutes (pure exercise, not counting going up and down stairs to take a bath and change clothes) is the golden length of aerobic exercise, that is, the first 20 minutes can consume stored glycogen, and the last 20 minutes can use fat as energy, which is not long enough to guarantee a certain intensity.

However, there are two issues that need attention. Aerobic exercise requires intensity. Try to control the heart rate at 140- 150. Too low or too high is not good. For example, going out for a walk, not losing weight, hurting your knees. Another thing is to keep your mouth shut. Don't think I can eat more after exercise today. Ordinary aerobic exercise consumes 300-400 calories in 40 minutes, and you will come back soon after eating snacks.