I'll try to name some.
When I was younger, I took a lot of physical risks not thinking much of consequences. I could have been paralyzed from the waist down easily when I fell from the top of a tree one time and landed on a swing set on my back. I was thrown off a go-kart death-trap like 3 times, one of which shaved off the skin on my side till I could stick my finger in and touch my rib bone. We accidently had a car roll backwards when we were all in it as kids into the street. doing stupid stunts like jumping over x number of newspapers lined up in rollerblades on concrete without pads not thinking eventually you come to a breaking limit where you can't jump over them and fall didn't occur to us really. We got into a lot of pretty awful stuff growing up. I think my mom just assumed we were going to die by the age of 15.
I enlisted into the military when I was 17 having no idea if that was what I truly wanted or needed in life, signed away 6 years of my life not knowing if I'd resent myself for years later or not.
Those are the big ones I can think of off the top of my head.