Gilbert Keith Chesterton wrote "I would maintain that thanks are the highest form of thought; and that gratitude is happiness doubled by wonder."  The most joyful and balanced people I know (some personally) are filled with awe, apprecation for surprise and a tremendous depth of gratitude.  And I'm not talking about people who have it easy.  One man I know was a NYC bus driver and, despite some very angry/impatient/moody passengers, maintained an amazing level of peace.  Why?  He was simply grateful to be alive!