Buy yourself a 1 pound dumbbell and practice it every day. Three groups a day, one group three times, 20 at a time.

These actions are:

1, clamp the boom and bend upward;

2. Hold the big arm and swing back;

3. Keep your arm straight back, hold the big arm and lift it.

These three movements are a group, and each movement is done 20 times. Take a break in the middle, and then do two groups.

It is usually valid for one week. Also, please control your diet properly.

This is my personal experience, which my fitness instructor told me. It is very effective.