You just have to keep working day after day. Word after word. You can do it!
One of my favorite books as a child was written by Elizabeth Coatsworth. The book was THE CAT WHO WENT TO HEAVEN. Elizabeth and Henry fell in love, but Elizabeth refused to marry Henry until he finished his book. You can read about Elizabeth here.
Ralph Waldo Emerson said: Nothing great was ever achieved without enthusiasm.
Inspiration is everywhere. Get to work.