Adulthood is where every decisions you make will either affects your present or your future. Where you should realize the burden of making decisions for yourself is on your own shoulder. Where you had a long list of things you want to do, but got neither time nor money to done any of it. When you want to spend most of your time at home. Where you get really really really really worried of your future.
I always tell myself it's okay to screw things up sometimes, but the I realize I've screwed so many things in my past. Now it's time to make everything right again.