Natalia Molchanova, World’s Best Free Diver, Vanished During Final Dive

Assume a comfortable position. Now close your eyes, exhale slowly and steadily, then draw a long deep breath, completely filling your lungs—and hold that air. Notice that as the seconds slowly tick past all of your attention turns inward, bodily. There’s pressure in your chest; you become more aware of your heartbeat. As the urge …