In the current edition of the Paris Review, there's an excellent interview of Norman Mailer by Andrew O'Hagan.
At one point in the interview, O'Hagan asks:
'Might it be said, in any event, that writing is a sort of self-annihiliation?'
'It uses you profoundly. There's simply less of you after you finish a book, which is why writers can be so absolutely enraged at cruel criticisms that they feel are unfair. We feel we have killed ourselves once writing the book, and now they are seeking to kill us again for too little... yet if you're writing a good novel they you're being an explorer - you're getting into something where you don't know the end, where the end is not given. There's a mixture of dread and excitement that keeps you going. To my mind, it's not worth writing a novel unless you're tackling something where your chances are open. You can fail. You're gambling with your psychic reserves. It's as if you were the general of an army of one, and this general can really drive that army into a cul-de-sac.'
There's an videoed interview here.