I can prove it: happiness is a photo book. In Emotional Equations: Simple Truths for Creating Happiness + Success, Chip Conley identifies equations that provide insight into our emotions. One equation that Chip presents describes happiness:
This equation leads to the obvious question: how do we ensure that we want what we have? Specifically, we need to appreciate what we have, and the way to do that is through taking photos and writing about our experiences. Only by documenting and remembering our life can we appreciate it. And what better way is there to document our life than by creating photo books that highlight the people and experiences that are most important to us? There you have it – happiness is a photo book.
All About Images Blog 
Totally agree! I tell people that kids don’t need 18 photo books chronicling every detail of their 18 years of life when they leave home but every kid needs at least 1 book that shows — through pictures — that they are loved, that they accomplished things (even if those accomplishments are kindergarten graduation and having a project for the science fair) and that they are better now than they were (see Child crawling, see Child walking, see Child running). That sort of thing should make any kid happy. So ditto goes for those of us who are considered adults — even one book that shows who loves us, what we’ve accomplished and how far we’ve come (all of which are “wanting what you have”) should contribute to our happiness.