I've been slowly making my way through Flow: The Psychology of Optimal Experience by Mihaly Csikszentmihalyi.
He talks about how important it is to have immediate feedback to get into the flow state (the flow state is the state of deep concentration that Csikzentmihalyi identifies as the common element in different reports of optimal experience). He talks about how the tennis player knows immediately (almost) whether the shot is in.
But does the dissertation writer have any such immediate feedback? Obviously, at one level, no: the dissertation writer depends on the professors who will ultimately sign off on the dissertation.
On another level, every writer has feedback: is there anything on the page? how much is on the page? is there anything useful on the page? Writers also have the experience of writing--are we engaged? are we focused or wandering? Those experiences themselves can tell us how we are doing.
Often I write something, or rather, I start to write something when I don't really know what I want to say and I'm just saying something for the sake of writing. Often, at such times, I am not focused and my attention is wandering; often my topic is something that I think might be interesting but don't know how to discuss. But as I expend effort to continue to engage with the writing, I begin to find greater concentration, and often I begin to find a greater sense of what I could say, and this helps me focus more: the actual process of writing helps me gain focus. Each word that I put on the page is something to reflect on, and I try to add to it, to refine it. In this way I have continual feedback that helps me focus my attention and move closer to both a coherent written form and to a sense of flow. But, though I strive for such coherence, and find it a nice challenge to see if I can manage to bring coherence into a single, completely unrevised draft, I have no expectation that I will get such coherence on the first draft. Or the second, for that matter. By the third, maybe, but...The more easily that you can write the first draft, the more time you have to revise, and the less intimidating it seems to have a revision ahead of you. If you have a day where you write very productively--you write a good ten pages, perhaps, or more,--then it's much easier to believe that you can have other such days, and so writing becomes that much less intimidating (and therefore that much easier).
In order to get your writing to generate immediate feedback, you need to write something. Let's, for a moment, just think in simple terms. If you're writing and you're struggling to write, and you write a sentence, isn't that a decent feeling? At least for a moment you can say to yourself "ah, I've written that sentence." And if you can write a whole paragraph, you can say "yes, I've written a whole paragraph," and so forth. So it's a good idea, if you're having trouble writing something, to just write anything. See how it looks on the page. See what could follow it; see how it could be built up. Put words on the page.
Sometimes I wipe away what I've written, but if you're struggling to write, you want to get words on the page. I have no trouble filling a page or three (in a blog, certainly, where it's a one-shot deal, and I won't usually even go back to clean up the typos and errors that come from changing my idea in mid-sentence), so if I wipe away a sentence or paragraph, or even page, it's no big deal. But if you're struggling, put words on the page. Give it a try. If you write a first sentence and say "that doesn't work", instead of erasing it, ask yourself, what would have to go with that sentence to remedy the error, and write that. Put words down on paper (or computer).
We have our best experiences when we're working hard, or so at least Csikzentmihalyi reports from his studies of people reporting on their optimal experiences. So how can we create a situation where we're working hard and that work becomes an optimal experience?
Csikzentmihalyi may give suggestions on how to achieve flow--I haven't finished the book--but, if flow states are characterized by concentration and by feedback, we can see that writing is a situation where those conditions apply, and it certainly takes effort. If we want to find flow in writing, the implication seems to be that we want to actually put words on the paper, because these will help us focus and will give us feedback.
Make mistakes. They give you feedback. If you make lots of mistakes, you can write several sentences in a minute. If you try to write a perfec sentence, you can wait hours with no result. Make mistakes, get feedback. Look at the words on the page and say "how do these help me write the next sentence?"