If you have a good build and know what you're doing, you can do well as a trainer.
Its even better if you have some form of college degree, especially if you dont have your own business and are working for someone--places like to see college degrees, even if they do not mean much. They just like to see that "diploma."
But, its obvious that Flinstone will not go to college to get a degree in an exercise related field.
Maybe with his build and a CPT certification and some other credentials, he can do okay for himself.