In any creative endeavor you have to give yourself permission to create junk. There is no way around it. Sometimes you have to write 4 terrible pages just to discover that you wrote one good sentence in the second paragraph of the third page.
Creating something useful and compelling is like being a gold miner. You have to sift through pounds of dirt and rock and silt just to find a speck of gold in the middle of it all. Bits and pieces of genius will find their way to you, if you give yourself permission to let the muse flow.
Words for any writer to live by. :-)