There is a zen koan about a visitor asking a monk about zen. The monk pours the visitor a cup of tea until the cup is overflowing. “It’s full!” the visitor says. “Like this cup,” the monk says, “you are full of your own thoughts and obsessions. I can only show you zen when your cup is empty.”
The same is true with writing. You sit and you wait. Maybe you read a little, or look out the window. In other words, you write out of silence, and staring into space, and total undistracted attention. Great ideas come out of emptiness.