The first world I made was an island that I drew a map of once in elementary school. It looked somewhat like a face and I made up some strange beasts to live in certain areas, and drew vehicles with many and weird weapons to patrol the different regions in my name. Later I redrew that map once or twice.. first because I had lost the original, and then because I wanted it more.. realistic.
Then in highschool, actually in senior high, (hey, I never claimed to be an adult) I discussed this with a friend, who also had an imaginary kingdom, only his had an actual piece of forest to be in, and showed him a symbol I had drawn once to represent a weird sound in a weird letter to a another friend (see? I have several). He thought I should make an alphabet, and not just one letter.. so I did.
I had read Tolkien's Hobbit and Lord of the Rings, and was fascinated by his invention of a whole world with languages and all, and I wanted to do the same. I played a little with making up a few words, and thought a lot of weird ways to make up a new universe. Then when I started at university I began reading a whole lot of fantasy, and I bought "The Shaping of Middle-Earth" which contains Tolkien's way to the final universe, and the thoughts behind it. That's when I seriously started jotting down how I thought my universe should be. While in uni I started writing a few stories set in this universe, finaly understanding that I'd never make up the whole thing or a whole novel in one go, and so far I've finished two. The last one was done years ago though, and I'm not optimistic about finishing, or even starting a new one any time soon.
I don't think I'll ever be a writer, I'm too lacy is one thing, but I have an imagination with lots of twists and turns, and I might as well write some of it down, and let you judge wether it's poor literature, or pure gibberish. I need encouragement to get going though, so if you actually want more, you ought to beg for it. ;)