Just remember some simple exercises every morning and evening.

1. Keep your legs straight and at right angles to your body (that is, sit with your legs straight) or keep your body straight.

2. Hands naturally hang down on the left and right sides, which can also support the body.

3. Keep your knees straight and your feet flat 10 second (your feet are straight and parallel to your legs).

4. Keep your knees straight, hook your feet up, and keep your legs at 90 degrees. 10 second.

5. The fourth and fifth items above are repeated alternately 10 times or more!