Physical training is like this. At first, the physical fitness was low, and exercise was to accelerate the burning of excess fat in the body. So when you start training, you will feel sore and tired. If you lose weight and improve your physical fitness, people will become very energetic. After exercise, you need to absorb energy from the outside, maintain body consumption and exercise consumption, eat a lot, and accumulate physical strength and muscle fiber.

This requires special practice, sit-ups, both ends.