I'd like to quickly address a current problem. I have injured my neck by sleeping on it incorrectly, and moving my head up and down (like to look down at my sketchbook) makes it hurt even worse. I'm falling behind on my comic pages, and it is awful. I believe in the idea that once you stop working for a good excuse, it opens the doors for making poor excuses to get out of it. But where should the line be drawn?
It's very easy to stop oneself from working on art. I think a lot of artists become experts in the art of self delusion and hold themselves back. "I'm not sure how to do this, so I'll wait and think about it." "Just one more refresh of facebook/tumblr/twitter and I'll get back to work." "Working on this is frustrating, I should just stop before I make myself angry." These CAN be legitimate reasons to stop working, if you allow it. It's all mental.
But there is a point when you do need to take control of your own life before you take control of your work schedule. Art is painful, on the wrists, the neck, and especially on your self esteem. Taking breaks for these reasons are important, you just need to know when you are taking them for your need, and when it is just for luxury. At least that's my two cents on the idea.