Derek Sivers, in his People & Blogs interview:

Do you have an ideal creative environment? Also do you believe the physical space influences your creativity?

Space matters, but when you’re really inspired and driven, it’s almost like going into a trance. You don’t care where you are or how comfortable the chair.

This is so true. Most of my best writing happens in wildly uncomfortable places and positions, with the least ergonomics. It doesn’t matter if the words are flowing.