33 years for me – good Lord! I have friends who have been in it longer. However, I never called myself a “Personal Trainer” until the late ’80’s. We were “Fitness Instructors” before that. The first person I remember to use the term “Personal Trainer” was Jake Seinfeld (Body by Jake). Of course the Founding Father is Jack Lalanne (RIP) who I had the pleasure of meeting about 25 years ago in Dallas. So to answer your question, I can’t. My guess is that the average shelf life of a Personal Trainer is pretty short, since I don’t know too many people making a full time living out of it. I’ve met plenty of part-timers over the years who got out of it all together – it was nothing but a hobby. I’d be very interested to hear stats on that. Sorry for rambling!