Invasion from Outside the Territory

A young man with low self-esteem and decadence actually became confident after being injured; The approach of a strange girl changed his life and awakened him from mediocrity; In the end, he not only resisted the secular world and finally got married, but also made his due contribution to world peace without fear of personal life and death when faced with the invasion of life from outside. How did he change his destiny and succeed in counterattack?