I can't find the exact quote now (because there are so many!) but a couple of years ago, I read something that R.L. Stine said that's really stuck with me. It was along the lines of, he believes that everything he writes is brilliant, and it's his wife who helps show him where he needs to edit. It was so refreshing because as writers we have this very conflicted relationship with our own skills. That was the first time I heard anyone say that they actually believe what they write is good.
On the one hand, we're supposed to be beyond modest. We have to make out that we don't really think anything we write is any good, lest we seem big-headed. It's fairly easy a lot of the time, writing can be deeply personal depending on your style, so sometimes it's easier not to talk about it.
At the same time, we have to show that we believe in what we've written enough to make other people want to read it. We either have to convince industry professionals that we're worth their time and money, or we have to relentlessly market ourselves.
This conflict makes things especially difficult now we're in the age of self-publishing. There's no time to be wasted pretending we don't think we're any good if we're trying to make our target audience buy our books. All we have is ourselves, playing the part of Agent, Publisher and Marketing Department. Maybe it's time we let go of the modesty, the self-doubt, and just accept that it's ok to say what we've written is good. I believe in my work. It isn't life-changing, Earth-shattering brilliance on every page, but I believe it's good, and well worth a read.