Dating my now wife, we lived in a city. She lived about 30 blocks from me and walked to her almost every night. Eventually, I bought a bike. I always wore a helmet.

One morning, I did this whole "I don't need to wear this thing... I never fall, I need my hair nice before work and everything will be fine. " Start riding. Two blocks later, I stop and tell myself, "Don't be dumb, put the thing on and stop being stupid." 2 blocks later, my chain pops while I'm pushing the pedal down, I lose control of the bike, fly over the handle bars, and smash the crown of my head/helmet into the corner of a brick wall. Crash to the ground in serious pain from my neck to my shoulder, down my arm, which feels like it's on fire with a pinched nerve... but my skull seems fine. I was literally on the opposite corner of a hospital I used to work for and the guy from the pizza place across the street saw my accident, comes running out, throws me and my bike into the back of his van and drives me to the ER entrance around the block.

I often think that if I didn't smarten up and throw on that helmet mid ride, I'd either be dead with a shattered skull or I'd have serious brain damage. Instead, I had a very mild concussion and a pinched nerve that resolved with 6-8 weeks. I'm very fortunate.