From Julia Cameron’s The Right to Write.Set aside a half hour:

Settle yourself in to write. First take ten minutes to describe where you are. (I’m in my office and furious.) Try to capture your mood, the room, anything delightful or interesting that catches your attention. Number your paper from 1-5. Very quickly list five things that would be interesting to write about. Choose one topic. What would you write about it? Why would you write about it? Spend five or so minutes writing about that.Do not go for Art, capital A, or even writing, capital W. Think of this instead as word play. Do not worry about being deep or sensible or practical.