I was in my tree house deciding whether or not I could see myself spending the rest of my life with this girl I had a crush on. It was first grade. Even back then as a child, I never felt like wasting time. I was always playing the long game.
I didn't realize I was old back then, but looking back, yeah, I was old to begin with. Truthfully though, I started realizing I was actually old when I didn't have time to learn to be good at video games anymore. Not only "be good at them," but I'm lucky if I can make it past tutorials anymore. They're just so darned complex now-a-days.
edit: Ahh, you said "moment." I'll get back to you.