Ceaseless optimism about the future only makes for a greater shock when things go wrong; by fighting to maintain only positive beliefs about the future, the positive thinker ends up being less prepared, and more acutely distressed, when things eventually happen that he can't persuade himself to believe are good.

The Antidote: Happiness for People Who Can't Stand Positive Thinking (ed. Farrar, Straus and Giroux, 2012) - ISBN: 9781429947602