Changed my approach
The other problem is that it's easy to freeze up if I believe I'm not writing well. The mantra "I only have 1000 words so they'd better be good ones" keeps running through my head.
The solution is easy: I've upped my daily word count to 2000, and at least half is allowed to be junk of the worst kind. I can easily convince myself that 1000 of the 2000 words will be useable, after editing, and that keeps me confident and happy.
And believe me, it's much easier to write 2000 words with no pressure than it is to write 1000 when under the pump.
(Bear in mind I spend the previous evening working out which 2 or 3 scenes to write the following day, so I don't have to stop and think a whole lot.)
The other thing I've done is to set aside the weekends. If I don't write anything then, tough luck ... it's important to have a life to go with the career. Yesterday we had a wonderful family day by the river, with a nice picnic and five mums in attendance. It was nice not to be fretting about daily word counts.