Ed Diener quotes:

Being too happy is bad for you. 8 on 1 10-scale is just right. Eg. cancer patients are more likely to survive if they're at an 8 instead of 9 or 10.

Psychological wealth includes life satisfaction, the feeling that life is full of meaning, a sense of engagement in interesting activities, the pursuit of important goals, the experience of positive emotional feelings, and a sense of spirituality that connects people to things larger than themselves.

It appears that the way people perceive the world is much more important to happiness than objective circumstances.