Stress
If you enjoy your work, then you're probably fairly stress-free—as long as you're making enough to eat (hunger can be stressful). If you don't enjoy your work, you're probably supposed to being doing something else, like designing houses or figuring out quantum mechanics. You know, boring stuff.
The good news is whenever you're feeling stressed, you can sit down and draw yourself a calm, beautiful world full of rainbows and tide pools and spaceships and unicorns—which you can then turn into a best-selling children's book. Now that's stress release.