I know this:
250 words, get up and get another cup of coffee.
250 words, get up and scratch the dogs' ears.
250 words, eat lunch.
250 words, declare victory and spend the rest of the day editing, chasing new work, bookkeeping or, better, yet, walking, working dogs, hunting, or working in the garden.
I'm happiest, sometimes nearly euphoric when I'm writing. I know from long experience, that I need to get my 1000 words in before mid-afternoon, after which my mind slows. I know that I'm tormented when I don't get my work done.
Why, then, do I fight it? Why do I so often sit, churn, and obsess rather than simply write "one true sentence?"
I often wonder if that mental interference or static is really destructive, a symptom of some character flaw or inborn limitation, or somehow essential.