George Orwell on writing:

"Writing a book is a horrible, exhausting struggle, like a long bout of some painful illness. One would never undertake such a thing if one were not driven on by some demon whom one can neither resist nor understand. For all one knows that demon is simply the same instinct that makes a baby squall for attention."

For myself, the demon shows up when he pleases, and when he does show up, he will rarely bother to do his job.