Here are some exercise suggestions that don't require equipment:

1. Push-ups: In most cases, you can train your arms by doing standard push-ups. When I first started doing this sport, I could do 20 push-ups a day. If you want to increase the difficulty, you can change the standard push-ups to one-handed push-ups, but don't force yourself, otherwise it may lead to muscle damage.

2. Flexion and extension of parallel bars: This action can exercise triceps brachii, but it should be noted that the descending angle should not be too large to avoid damaging the shoulder joint. You can use static movements to exercise your arms. After your arms are straightened, you can support your body with the strength of your arms.

3. Flat support: This sport can exercise arm strength and shape lines, but it needs long-term persistence. You can support the ground with your hands, keep your waist and abdomen straight and keep your body in a straight line.

In addition, proper diet and rest are also important, because good nutrition intake and adequate rest can help the body recover and repair damaged muscle tissue.