I used to do quite a bit of martial arts. Now a days I just practice BJJ, and some Judo. I also used to do amateur mma fights.

Kyokushin Karata : Green Belt

Brazilian Jiu-Jitsu: Black Belt

Judo: Brown Belt

I also used to box a little bit. Have thought about taking some Muay Thai kickboxing as it seems cool, but never really got around to it.

I recommend getting into some form of martial arts. It is great for staying in shape which I know you are all about, and it is a great way to get rid of unwanted stress and anger.