I had basically established a routine this fall, but NaNoWriMo really solidified that routine by putting pressure on to get to a certain word count every day. Single talks about setting time-based vs. task based (word or page count) goals every day. I had been using a time-based goal, but it was getting easy to scale that back or to otherwise waste that time and have little to show for it. Now I use a combination of time and task-based goals, with an emphasis on the time. Blogging generally has to occur before my writing time begins and I will put it off if I don't get to it before that.
For NaNo, I've been trying to write 3000 words a day because I'm behind and I do so during one set period of time. My basic rule now is 3000 words in two hours. I will go over that time if I'm close to meeting the 3000 word goal. Realistically, I can hit 1500 easy in that time. Getting to 3k is always a challenge, but a good one. I will quit at the two-hour mark if I am struggling to get the words out. No sense banging my head against the keyboard. Today I got to 2k instead of 3 and I think that's okay.
Single also mentions stopping when you've reached your goal, even you feel like you want to write all day. Other responsibilities will pile up if you take the day to write and you'll just have to put off writing to get those things done (laundry, anyone?). I don't think I've felt like going on and on ever in my writing life. There's always a point where I know I need a break. For years, I've been doing exactly what Single suggests below, and it's been extremely helpful:
Before closing down your document, write a few notes to yourself, notes that will jog your memory at the beginning of your next writing session and will help to get those creative juices flowing. Also make sure to type in your placeholder, such as the three asterisks I mentioned earlier, so you know where to start at your next writing session.I finished a section today and so tomorrow will start the next section. I spent the last 15 minutes of my writing session jotting down an outline and some key phrases that will help me begin writing the next section. I also keep a notebook by my keyboard where I jot down things that come to me throughout the day. Just because you quit typing at the keyboard doesn't mean that your brain doesn't keep working on your writing project. I also jot things down that I want to include (or think I want to include) but haven't written in the current draft yet. These are sometimes scenes, sometimes just concepts, like emotions I need to get across or descriptions I need to include. That, too, can provide fodder for the next writing session.
I'm behind on word count because I decided to take the weekend off. That had been my routine before NaNo, to only write during the week. I like treating writing like work where the weekends are time off, because it is work and while Dan Brown and Stephen King might work 365 days/year, we don't all have to.