Starting a Career in Fitness?

I was thinking about maybe getting a personal training certification or Exercise Science certificate (like an associate degree). I know a lot of people on the board are trainers and work in gyms and so forth, does anyone have an advice on starting a career in this field? Is the trainer certification the best way to get started or should I start taking the exercise science classes at community college or something?

I already have a B.A. in the humanities, but I don’t know if that will help.