Stress
The job itself is very low-stress. Sitting in a comfy chair, tapping away on a keyboard while doing what you love to do (or some version thereof).
But when it comes time to convert that love into dollars and cents, your head may certainly start throbbing. It isn't an easy life for most, so you'd better be prepared to struggle for your art. Besides, think of how richly your bank of life experiences will be enhanced when you have to stop your shopping cart on the sidewalk and ask someone for a quarter for the very first time! That's the stuff great literature is made of.