Altruism is the best source of happiness. There is no doubt about that.
You're happy when you help others become happy.
From a certain point of view our real enemy, the true troublemaker, is inside.
Certain beliefs must accompany every action: One should act without selfishness, cultivate compassion for all living things, and develop respect for others.
If you have a particular faith or religion, that is good. But you can survive without it.
Compassion is a mental quality that can bring us true lasting inner peace and inner strength.