I'm a 25 year old that has all but earned his BS in kinesiology from the University of Maryland. I'm in my last semester here and just have a couple of academic classes at the moment. As far as what I've focused on, nothing really. For my optional courses that are part of my major track, I have taken everything from the scientific basis of athletic conditioning, to neural basis of human movement, to sports marketing.
I have been a personal trainer for about 4 years now. Full time for some of it, part time for others. I'm part time right now. Most people that come in are your average Joe's looking to improve fitness, health, their physique, and occasionally strength or performance too. I have trained everyone from an 11 year old kid trying to lose fat, to a senior citizens trying to improve health/quality of life, to a 30 year old trying to look better naked and get laid while simultaneously recovering from a devastating skiing accident and subsequent surgery. I'm also a "mentor" at my gym. That is, I'm one of a few trainers who is supposed to have new trainers shadow them, have meetings with them, and asses their knowledge and competence before they start taking on their own clients.
I have been studying the topic of exercise science for about 7 years now. I have done a ton of reading on my own in the form of books, studies/journals, online articles, seminars/workshops, and discussions with other professionals in the field (Some being those who post on this forum). I do quite a bit less reading now than I have in the past because I usually have some kind of coursework to be focused on, so I like to have my extracurricular reading be something outside the realm of fitness on occasion. However, I still stay current, and I peruse a few fitness sites to see if there are any articles worth reading, though the majority of the time it's something I'm pretty familiar with already.
I also started training myself about that time. Although I started out pretty misguided, I have always worked hard and got some kind of results. I'm 6 feet tall, and I started at around 205. I dropped to about 160 after beginning to exercise like mad and undereating. I didn't do it the smart way, but I started doing something. Since then, I have moved up to nearly the same weight (Weighed in at 203 yesterday) at something like 10-12% body fat. So I basically lost about 40 pound of fat, and have since replaced it with about that much muscle.
My goals are almost always strength oriented, though I adjust my diet according to physique goals at the time. My best lifts are a 500 deadlift, 295 bench press, and 365 pound deep squat. Nothing marvelous, but decent. Also, my squats are actually below parallel, unlike most bullshit numbers people spout out.