Billy Wilder on writing

Interviewer: "What is your working procedure?"

Billy Wilder: "To quote Mr. Churchill, it's blood, sweat and tears, believe me. It is a drag. It is hard work. And it's not one of those kind of things people imagine that muses come kiss your brow, and there you are the poet in the clouds. Nothing like it.

From here, including a great scene on collaboration.