Knitting is repetitive, rewarding, and calms me down like a warm bath. But it takes up juuuust enough brainspace that I can't come up with ideas. Which is too bad, because I love multitasking.
You work for so long on a graphic novel that it's easy to question your ideas or to burn out on drawing. But you plug away at it and trust in the story you want to tell. It's a marathon, but the finished product is really satisfying.