Because fitness is different from boxing.
When exercising, let the muscles slowly congest, keep it for a while, and then release it. Let the muscles reach a full state.
Boxing, on the other hand, makes your muscles from a relaxed state and instantly send out great strength, that is, explosive force. Then quickly return to a relaxed state.
This force is mainly emitted from the waist, but the starting point is on the foot.
You are used to the previous state, and it takes a while to get used to it. This is the saying that changing boxing is easier than practicing boxing. When practicing boxing, the strength movements must be accurate. )
According to your waist, it is ok that you are not suitable for fitness and boxing. In fact, most people in China are not suitable for bodybuilding.
Martial arts and Sanda should not be taught to foreigners.