1. Diet control is the most important. The biggest cause of obesity is the unreasonable diet structure. It's hooliganism to talk about exercise without talking about diet changes, because it's too inefficient.

2. Swimming is still the aerobic exercise with the least damage to joints.

3. For the gym, it is recommended to use a horizontal bicycle. Backrest and seat share most of your weight, which has the least damage to your knee joint compared with other aerobic equipment in the gym.