Riding 25mph on a winding road, jogger coming the other direction had a dog on a leash. A car backfired, the dog tried to run, and it turned out the owner hadn't locked down the flex-lead, so the dog ran across the lane and into my front wheel. I went over the bars, did a tuck and roll to spare my head, ended up dazed on the pavement.
Aid crew came, checked me over, let me ride 12 miles home, slow and painful but glad it wasn't any worse.
Took a hot shower when I got home, which brought me out of shock, and my forearms swelled up larger than my calves, and my elbows wouldn't bend. Got a ride to the ER and found out one arm was broken in three places, the other in only two.
Never considered giving up riding. I managed to stay off my bike for almost three weeks before I couldn't stand it any more, and used a bench grinder to shape the casts to fit my brake hoods. Rode it on the trainer for a few days to get things adjusted for elbows that wouldn't bend, then got back to bike commuting.