Defensive pessimism can be reduced to a three-step mental rehearsal. First, approach the anxiety-producing task with lowered expectations, certain that it will go badly. (Take, for example, public speaking, a common fear: commit yourself to the idea that your next speech will be a disaster.) Then, imagine in detail all the ways in which it will go awry. (You will lose your notes at the 11th hour, you will trip on the way to the podium, you will be pilloried by your colleagues.) Finally, map out ways to avert each catastrophe.

For strategic optimists, the sorts of people who like to psych themselves up for a challenge, this routine would produce more anxiety, not less. But for anxious people, Norem's findings show that this unusual method can offer a sense of control, however limited, over uncomfortable circumstances.
—David Rakoff, "The Year in Ideas," The New York Times Magazine, December 9, 2001

The optimist, it's been said, sees the doughnut where the pessimist sees only the hole. Psychologists are nearly unanimous in recommending that you keep your eye on the doughnut.

But now two researchers are suggesting that for some people, a little pessimism may be a good thing. According to Julie K. Norem and psychologist Nancy Cantor, these people are able to use "defensive pessimism" to prevent the prospect of failure from immobilizing them. . . . The researchers conclude that when well-intentioned people reassure pessimists that everything will be fine, they may not be doing them a favor. Defensive pessimists may need to play their little cognitive trick on themselves in order to do well. The best way for them to get the doughnut may be to prepare for the possibility of getting only the hole.
—Carol Wade, "The power of negative thinking," Psychology Today, May 1987