I don't think the fitness instructor's words have anything to do with height, but have a lot to do with physique. After long-term exercise and training, you can reach the standard of a fitness instructor.
A fitness instructor should not only have a good figure, because it shows a result of your fitness, but also have a guiding spirit to guide others to do their own fitness work.
Now there are more gyms, many people love sports, and some people like to go to the gym to keep fit. I used to have a neighbor like this. Although he doesn't have that kind of personal fitness trainer, he still has a public fitness trainer.
Then I think a fitness instructor is very good and can guide others to help others.