Have you ever heard the advice 'face a fear every day' or 'surprise yourself with your own confidence'? During the incubation phase of creativity the subconscious mind continues to work on a creative challenge or problem and eventually an answer may 'pop into your head' as inspiration. I have a theory that the subconscious mind may withhold some ideas because it knows that some ideas, when 'presented', may make you fearful.
If you are in the habit of regularly facing fears then perhaps the subconscious may provide inspiration more frequently. The subconscious mind may also know that any ideas suggested may be confronted by the 'internal critic'. Using streaming techniques - write streaming, talk streaming or my own thinking-to-songs - could lower the resistance of the internal critic and invite the subconscious to provide more inspiration.
Just a thought. :)