You know how you sometimes find yourself in an environment in which there is a constant mechanical noise of which you don't become aware until it suddenly ceases? Maybe a refrigerator humming or a furnace or air conditioner or some constant traffic noise out in the street? And in that moment of cessation there's an "ahhhh" out-breath, a sigh of thanks, a relaxing of the shoulders? Yes, everyone knows this experience...
You were reacting to something in the outer environment with a tension-response, a stress-response, but you were completely unaware of it until the cessation of the stressor made you aware of your discomfort.
This is a lot like the situation in the mind of a spiritual seeker. Maybe you begin every day reading your favorite books, or sitting in meditation. Maybe you go to workshops or retreats and listen to spiritual leaders tell you how to get free of this feeling of unworthiness, or of just not "getting it."
Sometimes these experiences make you feel really good and you think, "I've got it!", only to find in the next day or the next week that doubt has crept in and once again you are your same old crappy self.
Or maybe one day, out of the blue, you have an experience of oneness or of light and bliss, and you think, "That's it!" and you spend the next several months wanting to repeat the experience and finding it more elusive than ever—a cruel drop of water to a raging thirst.
I'm here to tell you that within this analogy, YOU are the air conditioner. Your thoughts are the street noise. Your emotions are the sound of a pile driver in the distance. Your tiniest little thought about the past or future is the refrigerator humming. The slightest motion of your mind into thought, or narrative, or longing for something other than this, here and now, is the only problem you have—and it is voluntary.
The thought that you are not getting it, the thought that you are not enlightened, the thought that things should be better, the thought that you want what someone else seems to have, the thought that you ARE enlightened, the thought that you know more or better than someone else, the thought that you possess some special knowledge—any thought—any experience—anything but the silence of a quiet mind right here, right now, IS the stressor. There is no other stressor.
It's just an ingrained mental habit. Bring yourself back from thought, over and over, hundreds of times a day, whenever you notice yourself drifting into the narrative, the running inner dialogue. Resist the desire to entertain yourself with rehashing some experience or rehearsing some other experience. Turn away from it and into this here and now.
Do it whenever you remember. Eventually, finer and finer motions of the mind, finer and finer levels of undetected mental noise become apparent. You begin to discover that you have been tormenting yourself. You have been running the whole mechanical contraption. And the on/off switch has always been right in your own hand.