Learning to be a fitness instructor requires an exam. There are exams under the State Sports General Administration. Fitness instructors are generally divided into five levels. At least junior college degree and one year's experience in the primary examination. You can work in the gym for a year first, and then take the exam. No problem.

As long as you work hard, I think it is very reliable. If it's only three points of enthusiasm, then think about it before you decide.