Fairness
Ever felt like you're being treated unfairly? What's even worse is seeing the person who benefits from it walk away without being held accountable. I think, at some point, most of us experience this. What matters is how personally we take it and how much we allow the resentment to grow.
Speaking from my own experience as someone who hates unfairness and injustice, I can't stand the feeling of being treated as though I deserve less than I actually do. In the past, experiences like that would consume me mentally to the point where I couldn't focus or think straight. I would keep replaying the situation in my head, trying to make sense of it.
However, life has taught me something worth living by: karma is real. This isn't solely about religion or Buddha's teachings. To me, it's simply the natural cycle of life. People who choose to treat others badly for their own benefit or remain ignorant of the consequences of their actions will eventually face them. It might not happen in the same form or at the moment we expect, but somehow, life has a way of returning what we put into the world.
How about good deeds?
I believe the same is true for doing good. Our actions eventually lead us to what we deserve. Sometimes I see people say they've stopped believing in doing good because life has been unfair to them. I understand that feeling, but I don't think doing good should ever be a transaction.
The point isn't to be kind because you're expecting something in return. You do it because you're willing to, and because that's who you choose to be. If good things come back to you, that's wonderful. If they don't, your actions still reflect your character. To me, that's the beauty of it.