I inhaled and shut my eyes. There was a mental state I used to attain when I was playing soccer: my self would disappear, and I would be free, free of doubts and limits, free to focus on nothing but the game. When I entered this state I felt unstoppable. Sufi mystics and Zen masters would, I suspect, understand the feeling. Possibly, ancient warriors did something similar before they went into battle, ritualistically accepting their impending death so they could function unencumbered by fear.