ThIs is a great question. I'm not sure.
I think for me to be truly happy I need to feel like what I am doing is important, that life has some meaning and purpose and that I am living up to the person I want to be. That I am making some positive difference in the world and learning new things and experiencing new adventures and having real connections to other people.
Happy is feeling good about myself, when the reality of life comes close to matching the ideal picture of it I have in my head.
Maybe my expectations are too unrealistic.