" If we want to encourage people to do the most good, we should not focus on whether what they are doing involves a sacrifice, in the sense that it makes them less happy. We should instead focus on whether what makes them happy involves increasing the well-being of others. If we wish, we can redefine the terms egoism and altruism in this way, so that they refer to whether people’s interests include a strong concern for others—it if does, then let’s call them altruists, whether or not acting on this concern for others involves a gain or loss for the “altruist. "

― Peter Singer , The Most Good You Can Do: How Effective Altruism Is Changing Ideas About Living Ethically