An interesting post from the ever-interesting brainpickings.
[Martin] Seligman begins by identifying the three types of happiness of which our favorite psychology grab-bag term is composed:
‘Happiness’ is a scientifically unwieldy notion, but there are three different forms of it if you can pursue. For the ‘Pleasant Life,’ you aim to have as much positive emotion as possible and learn the skills to amplify positive emotion. For the ‘Engaged Life,’ you identify your highest strengths and talents and recraft your life to use them as much as you can in work, love, friendship, parenting, and leisure. For the ‘Meaningful Life,’ you use your highest strengths and talents to belong to and serve something you believe is larger than the self.
That's an interesting way to think about the nature of happiness. I would put myself in the "Pleasant life" camp with a certain degree of "engaged life" weaved into it, and sporadic spurts into "meaningful life" kind of activities, which usually don't lead to anything productive.
Seligman says "optimism" is invaluable to having a meaningful life. I think that's very true. Maybe even if I am not pessimistic, I am not quite the optimist.