I've been asked on many occasions how I manage to write so quickly (considering I'm a one finger typist) and the only answer I can give is that I enjoy the creative process so much. It would be so easy to procrastinate, go off surfing other websites etc, but I tend to discipline myself enough to work for 3-4 hours in the morning. I then take a few hours off and do the domestic stuff, spend time with my wife, go visiting etc, then come back to my writing in the late afternoon or evening where I go over 'what I wrote' in the morning and do a line edit and then usually this is enough to get me going again. Sometimes you can find me writing late into the evening (interspersed with answering emails, updating this blog, my website, facebook etc) and I find that the word count builds exponentially. I understand that not every writer has the luxury of the time I have - I certainly didn't prior to giving up full time employment - but it is a case of getting on and doing it. I recently read a line in a book (I think) where someone exhorts another to keep on keeping on - I've kinda adopted this saying as my work ethic.
So...keep on keeping on