The point of going to school is to learn, not to get an A.
The point of living your life is to grow, not to be happy.
In both cases, the latter is usually an indicator of the former, but there are ways to cheat to get the latter without the former. That's where people go wrong.
https://yourmeaninginlife.com/blog/happiness-is-not-the-meaning-of-life
The problem with any behavior is whether someone unwillingly is harmed or pays the cost of another person’s behavior—not who benefits. Therefore, both selfishness and altruism can be bad if it someone else ends up being harmed or paying for it.
https://yourmeaninginlife.com/blog/non-consensual-harm-or-expense-vs-the-greater-good
You don't have to save the world; your life and world get better one day at a time with every constructive act you take.
https://yourmeaninginlife.com/blog/you-dont-have-to-save-the-world
You can always find a reason to complain, and you can always find a reason to be grateful. The former will lead to a miserable life; the latter will lead to a more pleasant life.
https://yourmeaninginlife.com/blog/it-will-always-be-something