I've been skating since I was 10, though it wasn't till I was 11 or 12 when I found out about the skateboard world (I was a little ghetto country kid in a ghetto country bubble). I never quit, though I did have to take a break for around 4 or 5 months when I destroyed one of the discs in my back (non skate related injury in high school). Other than that, I've stayed on board and skated whenever I could. Skateboarding practically raised me... it's been the most consistent thing in my life for this amount of time, and there's no way I won't skate if I'm physically able to.
I've known a shitload of people over the past couple of decades that have quit, and for every one of those dudes that I still see on occasion (or talk to on MySpace), they all regret it*. They either tell me "they're gonna be getting a board soon" or "naw man, I'd bust my ass now." The latter of which makes me feel bad for them... I mean, I pay a mortgage, I've been rolling with the same girl for 14 years, I have a career, car payment, blah blah blah, and I bust my ass hard nearly every session I have. I don't like pain, but I'm still able to take it, so I do it gladly. I'm always coming into the office with bandages on my fingers, gashes, swellbow or a limp. I just love the fact that I'm still getting adrenaline rushes and still paying dues outside the office. I know I won't be able to skate forever, but I goddamned sure will while I can.
*I do know some people that got back into riding after our Dreamland park got built, but not enough people.