I still remember one of my highschool English teacher's quoting Chaucer: "The mind is its own place, and in itself, Can make a heaven of hell, a hell of heaven"

I've found this quote, and the generalization to personality traits in general, to be quite accurate. I've changed dramatically over the years.

It's important to note, though, that the biggest changes I've experienced occurred when I didn't have anyone around who knew the old me. Only then was I really free to explore who I could become. I think this is one of the beautiful things about anonymous online forums. They allow us to explore different mindsets in a way that wasn't possible prior to the internet.