Poets do not compose their poems with knowledge, but by some inborn talent and by inspiration, like seers and prophets who also say many fine things without any understanding of what they say.
Inspiration is not inside of us. Inspiration comes from outside. It comes from our spiritual guides and from different energies that are in the universe. If we keep in touch with god and our spiritual guides, just knowing that they exist and they are there for us, gives us the strength to say well this is a bad phase but it's going to end and when it ends I'm going to do something good.
I think what gets you through a small writing project, is just one burst of inspiration. A book, especially a longer book, it's a different kind of force that pushes you through it. It's a vision of the whole thing.