You are thin because you don't eat enough. Because thin people always feel that they have eaten enough, but in fact they seldom eat.
First, eat. Second, practice and rest.
The chest, shoulders, back and legs are aerobic. If you are tired, take a day off. It is suggested to sign up for a private class at the beginning and make the movements standard, which is equivalent to taking a lot of detours. In Tik Tok, there are many blogs sharing action teaching. Don't just watch the ten-second video that teaches you how to move. If you want to see it, look at the detailed analysis of the action.
In short, the following three points are indispensable.
Reasonable nutrition plan, intensive strength training, adequate rest and recovery time.