Usually, it happens so fast, your life doesn't have time to flash before your eyes, even if you're a youngster.
Ask me how I know that.
I'll give you one more.
We were filling silo, and I don't remember why, but I chose to stand on the "whirl" part of the New Holland Whirl 'N' Feed silage blower while the tractor PTO was still turning, as the "whirl" part was disengaged. Somehow, I lost my balance and fell against the Engage/Disengage handle. The "whirl" part started up, and then stopped very quickly...after my boot jammed it and it had ripped the toe off my steel-tipped leather boot. My bare toes were sticking out of that boot, unscathed. It did not happen to throw my leg into the "Feed" part of the blower.... Typically, we hooked up an IH806 to run the blower. It would never have noticed my leg, if such leg had been encountered.
-Paul