Dan Gilbert, author of Stumbling on Happiness, challenges the idea that well be miserable if we dont get what we want. Our "psychological immune system" lets us feel truly happy even when things dont go as planned.
I am the happiest man alive. I have that in me that can convert poverty to riches, adversity to prosperity, and I am more invulnerable than Achilles; fortune hath not one place to hit me. - Sir Thomas Browne