I love this quote from Art and Fear, a book by David Bayles and Ted Orland:
The function of the overwhelming majority of your artwork is simply to teach you how to make the small fraction of your artwork that soars.
I have a formula stickied to my desktop: you have to create over a hundred decent photos to make one that’s truly worthwhile. Making art can be frustrating. Very very frustrating. As you wait for inspiration to hit, you make a lot of mediocre art. I have learned that my best work is almost always an accident, an unintentional creation that blows all my careful work out of the water. Actively trying to create something rarely makes anything worthwhile. But the activity of trying to create puts me in a frame of mind where I am receptive to the worthwhile accidents along the way.