I think that this varies completely from person to person. There is not really any one thing that makes everyone happy.
For me, I have pursued happiness by trying to help create a stable and happy family. In pursuit of this kind of happiness, I quit my job teaching full time so that I could be the stay at home parent for my kids. This is not the same choice that everyone else would make.
I also pursue happiness by trying to learn new things. I like to read books about topics that interest me (right now I'm reading one about major scientific discoveries having to do with evolution). I also have continued to try to learn new languages.
So, I pursue happiness by trying to learn new things and by trying to help create a happy family.