Patient Husband once asked my why I write. Is it because I love it? I had to say no; writing is a slow, hard slog for me. Stephen King says he typically cranks out 2 000 words a day. I'm lucky if I can accomplish that in a week--when I'm not up to my eyeballs in schoolwork.
But the question remains: why write? My hobby used to be refinishing old furniture. I love to strip off old finishes, sand, and varnish wood, bringing it back to life and usefulness. At some point I realized that I liked it because I got a lot of pleasure from the simple act of accomplishing something concrete. Teaching is a fairly emphemeral task, and some days can be an exercise in frustration. I often compare it to tossing pebbles into a pond; it's difficult to see results beyond the ripples you've created, so it's nice to be able to point to something and say, "I did that."
Writing has taken the place of furniture refinishing. I like researching and gathering notes, learning about my chosen time period, and then working out what the characters do and say. Sketching out a scene, then polishing the draft gives me a similar feeling of accomplishment, and learning something new is fun as well. I have yet to realize the thrill that comes with publication, but I look forward to the day when I can point to a book on a shelf and say, "I wrote that."