I’ll leave it to the philosophers to debate the purity and existence of altruism; all that really matters to me is the end result.
Do your actions add to, or detract from, the social capital of the group you exist in?
Whether you sacrifice for the good of the group because you identify closely with other members, or because you feel a complex sense of indebtedness, or because you secretly want others to admire you, or because you realize being selfish is inherently pointless, or you realize that pleasure-seeking is actually a losing game, or all of these things, or other reasons… as long as you strive principally to rise above your own nature, I don’t think you need to beat yourself up over your underlying motivations.
Never give up. Never stop questioning yourself. Never stop trying to be better.
Never stop viewing yourself from the outside, and wondering how you would feel about you. “Am I beautiful on the inside?”
Do I embody the things I hold sacred?
Am I pure? What about me is tainted?
How can I burn away the corruption?