(No, really? You don't say!)
But that wasn't always the plan. When I started out in college I had no idea what I wanted to do. I studied a whole bunch of math because I was good at it, and when the major I was hoping for fell through, the easiest alternative was to fall back on a math major. I didn't realize I wanted to be a writer until my senior year.
Sometimes I wonder: if I had known then what I know now, what would I have chosen to study?
So, just for fun, here's a (not very well thought out) guide to majoring in "I want to be a fantasy writer."
2. Caveat: take lots of Linguistics. I only really understood English after I studied lots of other languages. (And I do love diagramming sentences. *sigh*)
3. Throw in a good bit of Anthropology. Roll a die to see which courses you get--you can hardly go wrong.
3a. Take an Anthropology of Music class. Music is a kind of magic, right? Decide you would rather be a musician. Drop everything, take piano lessons and become a composer.
3b. Take an Anthropology of Food class. (After all, people love reading long descriptions of every single meal your characters eat, down to the minute details of preparation.) Realize you'll probably be cooking for the rest of your life, so you might as well be good at it. Enroll in culinary school instead.
4. Take a Mythology class for inspiration. Add in some Military Science if you plan to have any warfare in your books.
5. Choose a track: Contemporary, Historical or Other-world Fantasy
5a. Contemporary. Take some introductory Biology, Chemistry and Astronomy. You can't break science with magic until you know how it works!
5b. Historical. Take a bunch of Medieval Studies classes. Come to the conclusion that there are enough Medieval Fantasy stories in the world, and that it was a rather brutish time period anyway. Take several History courses from multiple eras all over the world instead. You'll probably not hit on the one era you end up wanting to write about, but at least you'll know how to do research!
5c. Other-world. Take Economics. Geology. Political Science. Religion. A bit more Anthropology for good measure. Fight the disappointment that slowly dawns on you as you realize no world you design will ever be quite as real as the real world.
6. Add in some Psychology if you still have room for it.
7. Succumb to burn-out. Remember that you used to be so good at math. Wonder if you still might be able to make a career out of it somehow...
In retrospect, maybe my studies, unconventional as they were for a writer, set me along precisely the right path in the end.