Write at the same time every day.
You need to train your creative brain when to turn on and when to rest. Writing at the same time every day can help with this.
Even your sub-conscious benefits from a schedule, and your sub-conscious is where the majority of your story will be written.
For me, I like to eat a bit, exercise, and then sit down to write. Sometimes, I write for hours. Other times, I write for only an hour, but I always try to start at the same time every day.
Now, if I could just convince my sub-conscious to stick to my 9:00 a.m. writing schedule and stop working on my story between the hours of 10:00 and 11:00 p.m. Then, maybe I wouldn’t have to write so much of my book on my iPhone in the dark.