Stress is created by your mental processing of your experiences. It usually has to do with separation. Whenever a threat, barrier, or obstacle pops up, our immediate reaction is to pull back, to prepare mentally or physically to fight or run. If you become the barrier — become the fear, the pain, the anger — by experiencing it fully without judging or avoiding or running away, and then let it go, there is no barrier. Actually, there is no way to pull away from it; you cannot run away. There is nowhere to run to, nothing to run from; it is you.
— John Daido Loori, Essential Zen by Kazuaki Tanahanshi, editor, Tensho David Schneider, editor