Having confidence in your work

I ran across this gem of a quote in Tolkien's foreword to The Lord of the Rings:

Some who have read the book, or at any rate have reviewed it, have found it boring, absurd, or contemptible; and I have no cause to complain, since I have similar opinions of their works, or of the kinds of writing that they evidently prefer.

There is a delicate balance of self-confidence that a writer needs to strike. Lacking faith in your work won't win you clients, but being over-confident is a turnoff too.

Personally, I find in Tolkien's statement just the right amount of confidence mixed with humor. It's a good outlook for a writer, isn't it?