Now we come to the heart of the matter. Nulla dies sine linea. The Latin axiom "Not a day without lines" sounds simple--and it IS simple--once it becomes a habit. That's what 100 days of discipline is all about--building the habits that not only support your goal, they facilitate it. They make it easy.
Of course, the goal is to write more than a few lines. (We'll get to that later.) But the first step is to make writing a practice: habitual, necessary, a part of the rhythm that is your day.
It doesn't matter if it's Saturday and the world is taking a day off, if you're not "inspired," (highly overrated) if it's Christmas and you're cooking a six course meal for twelve, you're still going to have your coffee, right? And during the course of the day, you're going to perform at least a dozen other tasks--some good, some not- that your subconscious has been trained to perform without struggle.
Nulla dies sine linea.
We're talking one line here; excuses are not allowed. If you've just worked a sixteen hour shift (been there), or even if "your soul is as thin as a playing card" as Joyce Carol Oates memorably said (ditto), you can still open your notebook or your laptop and sit with your work for a few moments. You can still write your line.
Then, if possible, follow it with another one until you have a page or three pages or maybe even a chapter. But if all you have is a paragraph or a three word sentence, give it. Give it with all your heart. (More on that later, too.)
Then go to bed at 10 p.m. That's my cue...