Just a quick question.

If you have experience as a personal trainer and you want to do it again then talk to a few gym owners and see if they will allow you to do so.

Curtiss, also, with your experience you should consider starting your own class, any open store front would serve as a classroom.(or rent for a class period in the evening after hours) check with local school coaches, they have a vested interest in young people in good physical condition. Connect with local martial arts instructors and maybe use there gym for a class. All on you shoulders. Good luck