RE: Re the ACE study program . . .
Go for it now, Faythe! In my early 20s I decided I wanted to be a fitness instructor some day, when I had the perfect body. My friend who also wanted to be a fitness instructor convinced me to just do it, because I might never have a body that I would consider perfect. So I went ahead and took the training (this was in 1984, pre certification days) with her, and became a part-time group fitness instructor. I have never looked back. I got the ACE certification when it came out (it was called the IDEA certification then, in 1987) and have since obtained my OFC and Can-Fit-Pro certifications (they are from Canadian organizations). I'm now 40 and still teaching, 18 years later. And, no, I've never gotten the "perfect" body. If I had waited for that, I would never have become an instructor, and I would have missed out on a lot of fun over the last 18 years. I have met people I would never have met otherwise, and my role as an instructor has given me a self-confidence that I'm sure I would not otherwise have had. I also have a wealth of physiology and nutrition information (through attending upgrading courses and conventions over the years to maintain my certifications). It has given me something very different from my full-time field of information technology.
I would recommend that you go ahead and take a course, get yourself certified, and try teaching a few classes. A lot of people hate teaching their first class!! It is nerve-wracking and it's very easy to tell yourself you're not suited for this. But you know what? You may never feel "ready" -- I think you just need to jump in and try it. It's kind of like jumping off a high diving board. You are entitled to try it if you want to -- it's not a special club reserved for people who look a certain way. You have a passion for fitness, and teaching is a good way to share it.
Don't worry about people thinking or saying things about your physique. You are probably a lot more critical of yourself than they will ever be.