Time and again, I hear this from writers: "If I just had more discipline I would..."
Write my book. Finish the book I started. Write those essays I dream of writing.
But when has discipline alone worked to accomplish anything? It's not going to keep you on your diet unless you really want to feel healthier and you believe you can stick to it. It's not going to help you train for a marathon unless you really want to know what it's like to run across the finish line and you think you've got what it takes. Discipline will not help you write a book unless you're feeling inspired and committed to getting it done.
When we procrastinate or think about our writing more than we write, there's usually something deeper going on. Something that undermines our commitment. Fear. Doubt. Uncertainty. Judging yourself for not having discipline is only going to feed those feelings, and add a new one to the top of the pile: guilt.
Kindness is the antidote to procrastination. Honor yourself and your writing by putting an end to the judging. Pay attention instead. See if you can figure out what's going on under the surface to keep you from writing. That's your starting point---the place from which you can end procrastination.