My memories of literary agenting are of a very happy time and there are surprising reminders of it coming back now.
When you're sitting down and you're blocked and you just start writing and something in your mind just clicks, you start seeing connections and so on, you really do feel like you're channeling something else.
For a long time, I would write without music, because I thought it was distracting until I appreciated that it actually unlocks a certain unconscious productivity vault in my mind.