Start action: bend your arm (don't bend your arm very much)-push your arm forward to straighten it-bend your arm-straighten it (if you feel tired at first, you don't have to straighten it completely). Do this action repeatedly.

Note: In the repeated process of bending and straightening the arm, the hands are always closed as shown in the figure, and the fingertips are not separated forward! During this process, you should feel your chest pushing and push your hands forward until your arms are straight forward.

Do it at least 100 times a day (once for each stretching), 50 times in a group. Touch your chest after you finish, and you will feel a little protruding at that time. Hehe, there will be satisfactory results if you insist on it every day. This kind of exercise can be done standing, sitting or lying down, anytime and anywhere. If you do it lying down, you can increase the thickness of your chest!