I'm like Anna. I have to make sure all tidying and little jobs are done first - including things like nail filing and even obscure cleaning jobs that you only do once a year (OK, there is always an element of procrastination for me too!).
As for the smoking, I used to always have to have an ashtray and packet of fags on my desk and it was a habit I definitely associated with writing. However, I've fully given up and not had any fags since Feb and all those 'associations' are now gone. I don't even want a fag when I drink alcohol now, which is nothing short of a miracle. I don't know what the secret was to suddenly being able to give up and lose those habits/associations. As Nick says, the time must have just been right for me.