All in Mind
When James Stockdale was shot down in Vietnam, he was taken prisoner by the North Vietnamese. He spent seven years being tortured and subjected to unimaginable loneliness and terror. He had little choice over the fact that he was shot down, or that he was taken prison.
Mental strength was determined by the choices people made every day. It had a lot to do with their good habits--like practicing gratitude and maintaining healthy relationships. But what mattered even more than what people did was what they didn't do.