Altruism is some sort of sacrifice, for the sake of persons other than oneself. It is the selfless concern for the welfare of others; a motivation to help others. In many religious traditions it is an important virtue.
Getting involved in a cause you believe can help reduce stress, increase happiness, and bring more meaning to life. 
"The feeling you get from giving to those in need is a reward in itself."
"There is a power in love that our world has not discovered yet. Jesus discovered it centuries ago. Mahatma Gandhi of India discovered it a few years ago, but most men and most women never discover it. For they believe in hitting for hitting; they believe in an eye for an eye and a tooth for a tooth; they believe in hating for hating; but Jesus comes to us and says, "This isn’t the way." And this morning, I think of the fact that our world is in transition now. Our whole world is facing a revolution." Martin Luther King, Jr.
- Altruism Merriam-Webster Dictionary.
- Altruism Catholic Encyclopedia.
- The Hidden Power of Altruism By Elizabeth Scott, M.S.