I highly recommend Barry Schwartz’s talk about how increased choice does not lead to increased happiness because of disappointed expectations, choice paralysis and individuals blaiming themselves for not achieving perfection.
In addition, Daniel Gilbert, has an excellent talk on happiness and how humans have an amazing ability to create synthetic happiness that is just as real as happiness supplied from external circumstances and how we over-emphasize the happiness we will get from changes in our life (a promotion, winning the lottery, a new house, etc.). Once you hear the TED talk by Daniel Gilbert, you should read the comments below the talk. [Also good interview with Daniel Gilbert in NYT, 4/22/08 called “The Smiling Professor“.]
And for a very different approach, listen to Buddhist monk and photographer Matthieu Ricard’s talk on how to train our minds in the habits of happiness.