A very important part of writing is where and how you do so. For myself, complete and utter silence just gets me fidgety. Music, on the other hand, helps me focus on my story for hours on end. And focus not only means you can be at it longer, but also better. When I’m deep into it, I’m often thinking a couple paragraphs ahead, as well as for the overall plot, but juggling about a dozen characters in my head at once so that I am able to switch character styles as quickly as I can hit the Return key.
What makes this level of focus possible is the music, as well as such things as my friends knowing better than to call me while I’m writing. Choose whatever type of music gets you going for the type of story you’re working on, though I would advise against anything with lyrics, as you might find yourself paying more attention to the words in the song than the ones in your head.
Oh, and remember that there’s a body hooked up to that creative brain of yours. Don’t forget a sandwich or something for lunch, take a break at the health club of something when you’re finished writing and before you edit that night after dinner, and get outside a couple times a week.