Some twenty years ago a friend of my mother's saw her son off to carry out his military service. In my mother's retelling of the story, this son had always been rather sickly and introverted, and her friend was worried to death about how he would cope with the rigors of life as a conscript.
A few months later, my mother met her, and apparently all the worries had melted away. "My son looks healthy and brown from all the sun. It's true what that say: joining the military really made a man out of him."
It's an old Korean adage that doing military service—required of all South Korean males meeting the physical requirements—completes one's manhood.