I need to get into shape and martial arts is the way I want to do it. I get bored with things with no mental side--bike, treadmill, etc. What are the best martial arts styles if your main goal is to get a good workout on a regular basis? I went to see an Aikido class and really liked it but even the intermediate class didn't seem to involve a lot of aerobic activity. The caveats/background: I am tall and skinny and quite inflexible (high kicks will be a problem). I don't care about learning to be a good street fighter or about enterring competitions. Any thoughts on what would be good ones? (Aikido, Judo, Karate, Taekwondo, Hapkido, Jiujitsu, Kickboxing, Kung Fu/Wing Chun/WuShu, etc?) Any help would be much appreciated.