Exercising the baby's body is very important for their health and development. Here are some common methods:

1. Abdominal time: When the baby is awake, let them lie flat, and then put some interesting toys in front of them to encourage them to look up and turn around. This helps to strengthen the neck and back muscles.

2. Crawl: When babies can sit up and keep their balance, they can be encouraged to crawl. You can spread a cushion on the floor to let the baby crawl freely. This helps to exercise their limbs and core muscles.

3. Grab and pinch: Give the baby some toys suitable for his age, such as soft balls and building blocks, and let him try to grab and pinch. This helps to develop their hand-eye coordination and fine motor skills.

4. Stand and walk: When the baby can stand and keep balance by himself, you can provide them with some support, such as furniture or walls, so that they can try to stand and walk. This helps to exercise their leg muscles and balance.

5. Swimming: If conditions permit, you can let your baby take a swimming course suitable for his age. Swimming is a whole-body exercise, which can exercise your baby's muscles, cardiopulmonary function and coordination ability.

Please note that every baby's development process is unique, so before any exercise, please make sure that the baby has reached the corresponding development stage without any health problems. In addition, it is necessary to ensure the safety of the baby at all times and seek the advice of a professional doctor when necessary.