IMO

I think that for some people meaning has to be chosen. That is what I understand of existentialism. You can choose life or death. Since you're going to die eventually anyway why not just wait it out. Choose a meaning. This is one of the thoughts that kept me from committing suicide when I was at my lowest. Why not wait. And in the meantime experiment with different things to make meaning in your life. While I agree that helping others and society ( that includes the environment) can feel artificial when one chooses it for one's own selfish,needs,in the action itself meaning gets manifest. I help out in a little school here. At first I did it because I needed a place to go. After I started interacting with the kids, I found that even a little attention from an adult can deeply affect a child. I went to school for selfish reasons but unselfish reasons presented themselves to me.
I also need medication, though.
I never had fun when I was supposed to be having fun. I have fun now.
Happiness is not a superficial thing. It can create its' own atmosphere which is contagious. It is a gift we can bring to the world.
As I said, just my opinion.