The final paragraph of CS Lewis’ Mere Christianity is incredible. He’s speaking on the issue of how to truly live, and his point is that selfishness is not actually in our best self-interest.
Check it out:
The principle runs through all life from top to bottom. Give up yourself, and you will find your real self. Lose your life and you will save it. Submit to death, death of your ambitions and favorite wishes every day and the death of your whole body in the end: submit with every fiber of your being, and you will find eternal life. Keep back nothing. Nothing that you have not given away will be really yours. Nothing in you that has not died will ever be raised from the dead. Look for yourself, and you will find in the long run only hatred, loneliness, despair, rage, ruin, and decay. But look for Christ and you will find him, and with him everything else thrown in.