Great summary:

There’s an overwhelming amount of happiness research.

Forget incorporating it all into your life — merely remembering it is daunting enough.

I like to keep it simple: Remember the 4 P’s.

1. Purpose
2. Perspective
3. People
4. Play

Work those into every day and you’ll be smiling more.

Eric's article has details: http://www.bakadesuyo.com/2014/01/the-way-to-happiness/

play!!  my toddlers are good teachers for that one. :)

What's amazing is that we know this as children and then society / responsibilities make us forget.

and worry and fear and laziness get the best of us grownups sometimes!

I think that stems from understanding the consequences of things.

And knowing that things don't always turn out okay.

That is to say: the worry and fear and laziness are rational responses to the vicissitudes. 

Also worth reading:

http://pandawhale.com/post/23824/why-cant-we-predict-life-satisfaction-over-the-life-cycle-people-are-bad-at-predicting-what-will-make-us-happy