Not since I was 18 and that was just a couple overnighters in county lock up for fighting and other public drunken stupidity but I know from close friends all too well how easy it ease to stay in the system once it gets it's hooks in you. And that's not to say I wouldn't have done significant time for other endeavors if I was less lucky (some would say smart but I like to try to call things at face value).
Prisons are big business with a helluva rebill plan in place, congrats on getting out of the lifestyle and moving on.