Started doing Brazilian Jiu Jitsu about 4 months ago or so, and to be honest, I've never been in better shape. I go between 2 and 5 times a week (if my beat up body allows it) for at least an hour and a half, usually 2, and I love it. My coach seems to think I'm improving fast, so that always hypes me up for the next class and makes me want to work harder. The only reason I won't go is if I'm sick or hurt.
I've lost 15 lbs so far, my cardio has never been better, my beer gut has melted and it's given me something to look forward to when I get off work. My lower back, also, has never felt better. Also, I've been eating much cleaner as well, your body recovers so much better. I barely drink now, and my weed smoking has toned down a lot.
Only problem is joint and neck stiffness (most likely a bulging disk, I should get it checked out), but that's 20 years of skating for ya, and BJJ ain't that easy on the body, especially as a white belt.