This delightful cartoon is not me. I have a kick-ass work ethic when it comes to writing. I will write on vacation, in a hospital bed, in the middle of the night, one-handed with my arm numb from jiggling the fussy baby, on a playground chasing after a hyperactive child. I write on computers, notebooks, napkins, scraps of toilet paper.
(Yes, I have run to the bathroom when an idea hit me, and jotted things down on there.) If I'm stuck on one book, I'll work on another for a bit. Stuck on both, I'll do some blogging. This work ethic is not true for other aspects of my life (see cleaning/organizing) but as far as the creative process, I'm in it all the way.
And yet--sometimes, you just have to let the field lie fallow. Or perhaps a better metaphor would be let the fountain build up some water pressure.
Then you sit down to work and boom--the stuff comes bursting out.