Provided I live a healthy life and have no accidents, I can say I've lived about 1/5 of my life now.
I don't want to give it too much thought though.
I don't think I've wasted, but I wouldn't mind re-living it. It's not that I don't want to grow up, but I'm scared of it. I want it, but I'm scared of it.
If this is what it feels at 1/5, I can only imagine what it'll be like when I get to 1/2.