It must be nice when you are young, but the career of fitness instructor may really have an age limit. When you are 40 years old, or even older, you can't do this job, because you must at least ensure that you have the ability to act and can do some standard movements yourself. How else can you teach others? It is a good choice in the short term, because people nowadays pay more and more attention to their appearance and are more willing to go into the gym to change their body shape. Economic income and work intensity are good.