THE IDEA MIGHT sound insane to some people: You're going to pay money so you can go to a place every couple of days and get beat up. But, joining up to study a martial art can be extremely rewarding for your fitness and your overall well being. Picking the right system to study is crucial if you're going to enjoy yourself and, ultimately, stick with it. Here's a quick guide to help you figure out which one is right for you. And this list is just a start. There are plenty of other areas of study out there to explore, but these seven are likely the easiest to find. MUAY THAI/KICKBOXING What is it? The term kickboxing has become kind of a blanket term to cover anything that involves punching and kicking, but Muay Thai has a few distinct features. It's a centuries-old practice that comes, predictably, from Thailand. In addition to fists and feet, it also involves knee and elbow strikes as well as a form of stand-up grappling called clinch. Where you've seen...