There's nothing wrong with the evening as long as it doesn't affect the rest. As for how much, it depends on your physical condition.

Generally 10~20 groups, 3~5 groups can be separated by about 1 minute;

Note: Exercise should be moderate, whether in the morning or afternoon. As far as health is concerned, it is effective to start exercising at any age. Exercise more when you have time, but exercise less when you have no time. Just move, even if it's just a trick.

Exercise needs vary from person to person. Instead of sleeping at night, do not exercise before doing sit-ups in the morning. This is a bad habit. I can't sleep well after exercise because my muscles are tight during exercise, and sleeping is relaxing. Let me give you a metaphor. You have to do it step by step. Don't do too much exercise at first, and gradually increase the amount of exercise later, instead of simply doing it, you can solve the problem. In addition to heart rate, there is also the simplest way to measure whether exercise is excessive. If you are out of breath during exercise, you have exercised too much.