Re: How do I become a personal trainer?
Aside from a college degree in some area of fitness/nutrition, certifications are the way to go. Most certifications have their own program/text/test.
ACE is the "basic" cert. Widely recognized, but not really good for info. Mostly resume fodder.
ISSA - a little better than ACE, can also get more specialized certifications.
NSCA/CSCS - much more difficult cirriculum and in the field, considered to be of more practical use. More respected.
ACSM is considered the gold standard, but I believe it requires a college degree.
IN THEORY, you don't need any certification to call yourself a personal trainer, but in order to get jobs at gyms or to show potential clients that you have an idea about what you are doing, it is pretty important. Google for each of them to find out more about what you need to do to get the certs you're interested in and what they cost, time frames and so on.
Keep your body lean, your blood clean and your mind sharp. -Rollins