It’s all about momentum.
Before I can even start writing a big project like a novel I have to do research and build the back story. That’s like fueling the carrier, getting the crew, marines, and air wings aboard.
Once that is done I can set sail with my outline acting as crude navigation to steer me to my far away port, a finished novel.
If the novel goes well, I start gather real speed in the writing and it takes a life of it own. Pages start flying by and the words just flow from me to the page. It takes  awhile for this to occur. The first ten or twenty pages are usually me fumbling about trying to find the voice and the path I need to take.
Lately I’ve been churning out nearly 8 pages a day on Cawdor. This has been a really productive time and its made me quite happy.
Monday the crippling headaches brought all progress to a rapid halt. I got nothing done, yesterday the headaches and the exhaustion from a bad nights sleep reduced me to less than two pages of text completed. I was really depressed today when at my first break at my day job the headache had returned and robbed me of even more writing time. I managed just 30 minutes of writing during my hour lunch.
Luckily i seemed to have found the steam again and finished up with about five pages completed, but it’s been tough getting that momentum back up.