That happens... a lot, when I hit 18 I was confused, frankly I did not feel like an advlt, then when I became 20 I got confused because I had no idea what I wanted to do or what I was doing with my life. I decided that I'll rather be under my pillow fort, coloring.
But being an advlt happens, bills to pay, taxes to do, work to do, and suddenly you're managing your time, thinking what's worth your time and energy and what's not, arguing over X in a video game? Sorry, no can do, not worth my time, I'll rather take my dogs to the backyard, and have all three of us play with them (Those are the fun days!)
You just don't put up with things like you used to before, but that's just me.
Turning 23 this December, been getting the occasional grey hair since I was 14, yay genetics!
Time does go by fast, this year is about to end and it feels like it just started. Looking at my family history, if I don't loose my sanity, or perish somewhere else, I have around 60-70 years ahead of me. It's both scary, but at the same time before I know it, I'll be there. Yelling at kids to get off my virtual lawn, because Google is out of virtual grass seeds.