What should I do after I am 40 years old?

It depends on the actual situation.

If you have switched to management, don't worry, but it is not recommended that you switch to management without goals, because your age does not allow you to fail, so I suggest that you switch to management as much as possible in the early stage. If it doesn't work out, it is recommended to change careers as soon as possible and have new development.

In addition, after you are close to 40 years old, many companies are unwilling to accept it because you may not adapt to the corporate culture.