ACE is now the easiest certification to get in the world of personal training. Others are your ACSM and NASM certifications. I believe the NASM is the toughest to achieve. A good route to go is get those while going to school, snag your bachelors and then become a CSCS. (Certified Strength and Conditioning Specialist)
I already went to college with an engineering major. Don't really want to go back. Just looking at something I think I'd enjoy when I retire in a few years. BTW, I check out of some the sample tests for ACE. Here was one of the question:
Which CANNOT be used by the body as an energy source during a high intensity weight training session?
a) Protein
b) Carbohydrates
c) Fats/Lipds
d) Vitamins.
Of course I answered vitamins as vitamins provide no energy, no calories. But I was marked off wrong and they gave the correct answer as Protein. WTF? There a couple of more that were either inaccurate or simply wrong. I think they charge $200 to take the test.