rom the excellent book "How to Fly a Horse".

Replace writing with photography as the concept is still the same:

“A victim of “writer’s block” is not unable to write. He or she can still hold the pen, can still press the keys on the typewriter, can still power up the word processor. The only thing a writer suffering from writer’s block cannot do is write something they think is good. The condition is not writer’s block, it is write-something-I-think-is-good block. The cure is self-evident: write something you think is bad. Writer’s block is the mistake of believing in constant peak performance.”