In an early entry in Thoreau’s journal, he writes this about writing. He was 23 at the time:
Let the daily tide leave some deposit on these pages, as it leaves sand and shells on the shore. So much increase of terra firma (solid earth). This may be a calendar of the ebbs and flows of the soul; and on these sheets as a beach, the waves may cast up pearls and seaweed.
The same applies to any type of writing. For a poetry manuscript or the first draft of a novel, writing for a long-term project requires resilience against one’s own whim to do something else. Even reading cannot encroach into one’s writing time. Bit by bit, the circumference of words begins to increase, and if you keep up with the habit religiously, soon enough you’ll be sitting on fifty, hundred, hundred-and-fifty pages of raw material.