The subconscious?

Anything by Carl Jung will do.

you might want to check out some of the back posts in this blog: http://www.adaringadventure.com/blog/

Life coaching might help. It's not therapy, you're assumed to be competent and together but just want more out of life.

Meditation will also work. Or daydreaming in a silent room, staring out a window at a single object, or something in the room. Looking into a fireplace fire (the flames) as well.

Relax totally and let your mind wander where it will ...

If you are familiar with the radio program Radio Lab, there was an episode where they were talking about creativity. Tom Waits had a neat approach - he talks to his muse. It's apparently a well-known method of his. Once when trying to rewrite a short story for the fourth time (the first three attempts were dreadful), I decided I had nothing to lose and tried it. I spoke out loud and and asked my muse what it wanted to show me. It actually worked.
I've used that trick a bunch of times now and have had great success with it. You could easily substitute something else of 'muse' depending on your goal. It's really just a trick to open yourself up to whatever comes.
It's not quite what you were asking for but I figured I'd put it out there anyway, just in case it's helpful.

"Thinking Write: The Secret to Freeing Your Creative Mind" by Kelly L. Stone. Has loads of great exercises in it. Reminds me, I ought to give it another read.

Try "The Dark Side of Light Chasers" by Debbie Ford. I could have sworn I've read others, including Jung but I can't find them at the moment. I'll update if/when I do.

If you are looking for something in the psychoanalytic tradition, using the keyword "unconscious" will work better.

Alcohol, grass, and/or prayer might help.