I train Brazilian Jiu Jitsu and a bit of no gi grappling. Grappling is one of the few things that can get my mind in exactly the place where it needs to be. Nothing makes feel as energetic and happy about myself as a good rolling session does. You get great cardio training, have lots of fun, feel good about yourself and time really flies when you're rolling. Also nothing feels quite like it when you've trained a new move for some time and you finally pull it off in a fight. I don't think it's a coincidence that most people who try out BJJ and stick with it for some time fall in love with the sport.
If you get the chance to try no-gi grappling or BJJ out, by all means do. Many people are afraid of being in too bad shape, being too heavy, too light, too young or getting smashed by more experienced practitioners at training. However, there's no need to be afraid. The BJJ community is probably the most newbie friendly community I've ever seen and physical attributes don't really matter that much when it comes to grappling, technique trumps everything else.