From David Farland's Daily Kick in the Pants:
When I was young and newly married, I used to sit down to write, and my wife would immediately think that “since you’re not doing anything, let’s have a conversation.” That’s a frequent problem for those who work from home. It might not look like I’m busy, but sometimes I really am busy.
In order to write, I have to get into what I call my “writer’s trance,” a state where I’m vividly dreaming about my world (with my right brain) while composing and analyzing my prose (with my left brain). So I have to work with full mental capacity, and it can take about ½ of an hour to get into that state deeply enough to get some good work done. So, if I’m in the groove, don’t bother me. I need time to focus completely on my work.
I've found that having a discreet but limited amount of time to write is perfect. If I have all day, I will definitely not spend all day writing, even if that's what I've been craving for weeks, months. Instead, I'll read some things, watch some things, play some things. Whereas if I have only, say, an hour before I have to be somewhere, so long as there's no distraction I can get into the writerly headspace pretty efficiently. However:
Your writer is insane. Remember that your writer spends a great deal of time in a dream world, talking to imaginary people, visiting places that don’t exist. Shakespeare often lamented about his poor mental health, wondering if he was a genius or a nut. He was obviously both. I once heard a psychologist say that “most writers are provably borderline schizophrenics.” I know that I am. I’m a science fiction writer, and being spacy is a job hazard.
...Getting back out of the writerly headspace can be a challenge. I tend to miss train stops and spill things on my pants. How about you?
Link to the rest here.