personally
if you think you can study a good amount and retain it, then do the NSCA or ACSM. I just got my NSCA cert last month... yes the test was somewhat difficult. If you aren't that "intelligent" I suggest you don't try the NSCA or ACSM.
What is good about NSCA is that you can really hype the fact of it being the ONLY nationally accredited cert. They send you out a lot of help on how to advertise and doing press releases.
I'm going to take a couple classes like anatomy (refresher), physiology and kinesiology and then get my CSCS from the NSCA.
You can make a ton of money if you think beyond regular PT'ing. Think group exercise "boot-camp" types of training. Thats where you bring in big bucks. Buy you will only get that type of thing going if you have a couple certs or college degree(s).
I have my BS in health services administration and my CPT cert from NSCA. Next is a degree in Exercise Science, get my CSCS (certified strength and conditioning specialist), and get ACSM cert'ed.
You get all that and you resume for training people looks really damn impressive.
Meet the right people and you end up training semi-pro or pro teams. Then you just PT people in spare time if ya want.
Luckily I live and work in orlando, fl where some NFL players workout and I've become pretty good buds with their trainers.
