The planet part is easy. I'm from a small planet somewhere in the vicinity of Betelgeuse, as you can tell from my profile.
On a more serious note, my primary interests lie in the sciences. I love physics and astronomy, and I hope to major in astrophysics in college. I'm always reading something new. I find that looking so much at other worlds makes me appreciate this one just a little bit more.
What do I do on Worldbuilding? I provide an endless source or annoyance for those who hate high-school algebra, focusing on the planets, stars, astronomy and physics tags. In real life, I go to a STEM school, and in my free time I do some self-studying. Oh, and I maintain a social life and athletics, too, believe it or not. But my love is science.
When I was younger, I used to read all the fantasy books I could. My favorites were Brian Jacques' Redwall saga. I spent nearly as much time poring over the maps he drew as I did reading! Well, not really. But I learned to delve deep into the world he came up with. I went beyond the story and imagined what it would be like to live in that unnamed land.
The books I read now are a bit more complicated, but every now and then I look back and re-read some of those old books. I guess that's why I love world building and story-telling. Maybe I think that someday I can get to that world where I lived when I was younger.
Imagination can transcend the boundaries of what we think is possible and send us leaping across worlds. That's what drives me.