I think I get this from Bruce Gilden as a photography assignment: shoot what you’re afraid of. Totally makes sense. If you see something which scares you, it probably interests you. And the more you can harness your fear and adrenaline in order to make more epic photos, the better.
Like Jimmy Iovine says:
Don’t let fear get in your way. Instead, you harness the fear and get it to push you ahead from behind!