"Those who find their lives will lose them. But those who lose their lives ... will find them" or "If you find your life you will lose it. But if you lose your life ... you will find it"
This does not mean to die. It means to consider obeying Jesus more important than one's own life. See how you translated "for my sake" in [Matthew 10:18](../10/18.md). Alternate translation: "who denies himself for my sake"