Stumbled on this today at The99% - makes a lot of sense:

“There are certain things I do if I sit down to write. I have a glass of water or a cup of tea. There’s a certain time I sit down, from 8:00 to 8:30, somewhere within that half hour every morning. I have my vitamin pill and my music, sit in the same seat, and the papers are all arranged in the same places. The cumulative purpose of doing these things the same way every day seems to be a way of saying to the mind, you’re going to be dreaming soon.”  - via Daily Routines