When you're relegated to go from movie to movie, so much of what you're doing is out of your control beyond creating the product.
The jokes I used to do on 'Sex and the City' were always comic character things, and they were rarely hard jokes. As soon as you go up in front of people, it demands laughter.
Writing is so wrapped up in ego, but with math one is just trying to get it right, although you're often wrong. I think math helped me become a good critic of myself, come at writing a little less personally.