Dan Gilbert: The surprising science of happiness | TED Talk

Conclusion:
"We should have preferences that lead us into one future over another. But when those preferences drive us too hard and too fast because we have overrated the difference between these futures, we are at risk. When our ambition is bounded, it leads us to work joyfully. When our ambition is unbounded, it leads us to lie, to cheat, to steal, to hurt others, to sacrifice things of real value. When our fears are bounded, we're prudent, we're cautious, we're thoughtful. When our fears are unbounded and overblown, we're reckless, and we're cowardly.
The lesson I want to leave you with, from these data, is that our longings and our worries are both to some degree overblown, because we have within us the capacity to manufacture the very commodity we are constantly chasing when we choose experience."