From the StoryGirl about Writing is Work:
For me, the best way to conquer that is to schedule my writing in as if it was a job, even when it isn’t. To get dressed, turn off the TV, log off of any social networking or chat sites, and not let myself do anything but writing until I’ve either reached my goal or the time has run out. Once in a while it’s pure drudgery and torture. Sometimes – most times – it’s a delight, and by the end I’m very glad I did it.
I am not very good at being disciplined at writing or almost everything else. One thing that does help me is making a plan and then sticking to it. If I have a plan, all spelled out, I’m more likely to get everything (or at least many things) accomplished from that list.