The way I see it is if you've never fallen out of a tree at height as a kid, road in the back of a pickup (sometimes sitting on the edge of the truck bed or dangling feet off the back of the tailgait or sitting on the 'wheel hump'), never crawled under your front porch to find bugs and have never fallen through ice when trying to walk across a frozen tree that fell across a creek you've never lived.
I'm littered in scars from a bike. It wasn't until I was about 21 that I stopped riding BMX due to injuries and things hurting a lot more as an adult as they did as a kid and a teenager.
Nowadays kids are pampered.
Got a scratch? A scrape? A cut? Rub some dirt in it you pansies.
EDIT: I was under my house and front porch last year to run leads for some IP cams and NOPE NOPE NOPE. As a kid I'd not think twice about crawling under there. As an adult: spiders. Nope. Luckily it was winter so those bastard spiders were frozen.