Nothing.
I try to avoid crashing or falling, though, of course, stuff happens. However, through 50+ years and well over 100k miles I've managed to limit my injuries to lost skin (sometimes, lots of lost skin). I did break my big toe riding, but that was at home riding rollers so I don't count it.
Yes, it's possible to be seriously injured on a bike, but with decent riding skill and good habits, the odds for a long and safe riding career are in your favor.
__________________
FB
Chain-L site
An ounce of diagnosis is worth a pound of cure.
Just because I'm tired of arguing, doesn't mean you're right.
“One accurate measurement is worth a thousand expert opinions” - Adm Grace Murray Hopper - USN
WARNING, I'm from New York. Thin skinned people should maintain safe distance.