Why should we care about nature? Yale Psychology professor, Paul Bloom, answers for The New York Times:

http://www.nytimes.com/2009/04/19/magazine/19wwln-lede-t.html?_r=3

Over 4,000 books on the happiness subject have been published in the past ten years. It seems to be the most sought-after yet elusive thing people crave.

So what’s the problem?

It could be our too-high expectations.  It could be our outward-rather-than-inward focus.  It could just be our definition or (mis)understanding of happiness. 

Frankly, I think the real problem is our lack of self-affection. 

So, instead of thinking that we must improve our material, physical or relationship circumstances, we might just want to focus on all the things about ourselves that are good and comforting and fun and promising.  That puts us square in the essence.  On the journey.  In the moment.  And, it makes happiness just one changed thought away.