"In the process of working with the breath, the thoughts that come up, for the most part, will be just noise, just random thoughts. Sometimes, however, when you're in a crisis or involved in something important in your life, you'll find that the thought, when you let it go, will recur. You let it go again but it comes back, you let it go and it still comes back. Sometimes that needs to happen. Don't treat that as a failure; treat it as another way of practicing. This is the time to let the thought happen, engage it, let it run its full course. But watch it, be aware of it. Allow it to do what it's got to do, let it exhaust itself.

Then release it, let it go."
Zen Meditation - The Seat of Enlightenment