What is work? What makes work "work"? What defines it?
One large aspect of what defines "work" in the culture of the US is that it is unpleasant; Work is opposed to play. That's a simplification, of course.
But what if work could be approached with excitement and enthusiasm instead of as drudgery? Maybe we don't all have the opportunity to find excitement and enthusiasm in our work, but surely, as an academic, or as one who might otherwise view writing as work, you must in some way be following something about which you had enthusiasm and excitement.
If you got into an academic program because of your interest in some idea, or because of your intention to accomplish some goal, that possibility still stands before you if you're struggling to write your dissertation. Being able to look again at that goal and examine whether it is still what you want to accomplish can help look at the work of writing in a different way.
If you have to work on something everyday--day in, day out--that can really detract from the pleasure of something. The sense "oh, I have to do it" can be so unpleasant that it overrides any pleasure in the act. The sense of repetition--that one has done the same before, and mindlessly will continue to do so--that also makes for an unpleasant experience. But writing is not digging ditches. Writing should be a process of learning. And learning can be gratifying in itself.
It's easy to look at work as a burden, and nothing more. That view can really weigh one down and sap the energy to proceed. If you can find a more positive framework in which to view work, then there is a greater will to succeed, and greater energy for the project.
The question, then, is whether there is anything more to work than the simple bearing of a burden from now into the future. I believe there is, but the argument is not one that can proven logically.