In 1977, Natan Sharansky was thrown into a Soviet gulag, confined to a freezing cell designed to break his spirit. To the guards, he was a prisoner; to himself, he was playing for a world championship on the board in his mind. To avoid despair, he spent nine years playing thousands of mental chess matches against himself. He rehearsed focus, poise, and victory with such intensity that his internal world became more real than the stone walls.

Years later, free at last, Sharansky sat across from Garry Kasparov in a friendly exhibition… and won. But the score didn’t matter. The real victory had already been won in the cell. Years of imagined endgames had kept his mind sharp and his spirit unbroken.