One of the downsides with almost all of the great writers I know is that they are, intrinsically, insecure. It's probably what makes them good, what keeps them improving. Unfortunately, it's also hell to live with. Affirmation is scarce out there, and if you are foolish enough to think either the markets (where all of us can think of quality sinking and drekk floating -- it's the little bubbles of rotteness in the drekk, whereas gold sinks) will provide, or the editors will encourage if you're good, let me remind you that the world's most popular sitcom (Fawlty Towers) was almost canned by the Beeb's editorial staff, and made very, very little money right through the first run of the first series.
It reaches the 'why am I doing this point, with the n-th rejection, or with the royalty statement figures that seem to show your career is going nowhere. I say 'seem', because I am not sure -- outside Baen -- how honest and accurate these are. They might be, but if they are - why keep them secret? (Jim learned a hard lesson I don't think he ever forgot, when Norman Spinrad tipped the fact that the company he was working for then (not as the bloke who was responsible , but as one of the staff) was about to be audited by the SFWA accountants. Apparently there was a lot of frantic work done and disaster was narrowly averted.) I'm very grateful for what it did for Baen Books, but I have often wondered if would not have done the whole industry more good to have had the publisher caught out, just as I think rescuing bankers was a poor idea (depositors, yes). I wonder if transparency - about advances, Nielsen Bookscan figures and sales would not serve the whole industry better than the secretive way thing are now done (which does a few individuals good - protecting their inadequacies - which is not good for the biz). Anyway. I was at one those why-am-I-doing-this points myself a few days back. Trying to work on proposals, a book that now has no plot (but a contract) and worrying a lot because a contract and the money from it was very, very late (the contract got to me). I needed some scrap paper to make notes. I keep a drawer full of old manuscripts for this purpose. Someone had been offering prayers to Anoia on my behalf, so, despite closing perfectly, much time, effort and bad temper was used in moving enough things to get my hand around the back of the drawer and pulling out a few sheets of red-ink covered paper... from one the first stories I ever wrote fifteen years back.
If you're a writer, needing to fight off the 'what have I achieved' depression, try reading your first first-draft manuscript. And if you're just a reader, now, in this bleak economic climate when so many retail, distribution and publishing albatrosses are coming back to roost (and dragging authors down with them), do your favorite authors a favor and write them (and their publisher) an e-mail telling them how much you love their work.