Apropos of nothing in particular, when I first started mountain biking, a guy I was riding with told me: "You can divide all mountain bikers into two groups: the ones who have broken their collarbone, and the ones who are about to break their collarbone."

Knock on wood, 20 years later I still haven't broken a collarbone, but I've had plenty of scrapes, bruises, cuts, etc, a couple of concussions, a torn rotator cuff, and quite probably a broken neck (never went to the doctor to have it diagnosed, but I landed on my head hard enough to crack my helmet and knock me unconscious for a few minutes and my neck hurt for like 6 months afterwards).

Still, wouldn't trade it for anything in the world. Nothing like being out in the woods, on a bike.