seriously before bjj, i used to have a little bit of a chip on my shoulder
afterwards, I was more serene and friendly with everyone around me, at work and beyond. Everyone noticed a difference in my attitude. I spend lots of time playing back previous matches in my head and remembering everything that happened during class and such. From grabbing the kimono of a 300+lb guy and sweeping him from the top of me, onto his ass; to toughening up and sparring with a guy, that kicked my ass and sent me home with cuts and bruises the day before.
Stuff like that keeps me at peace because it releases a lot of built-up energy and tension. plus it's like the ultimate chess match...and that in itself is pretty fun and entertaining.