The Wall Street Journal describes a technique I often use and rarely hear discussed:
Just thinking in sober detail about worst-case scenarios—a technique the Stoics called "the premeditation of evils"—can help to sap the future of its anxiety-producing power. The psychologist Julie Norem estimates that about one-third of Americans instinctively use this strategy, which she terms "defensive pessimism." Positive thinking, by contrast, is the effort to convince yourself that things will turn out fine, which can reinforce the belief that it would be absolutely terrible if they didn't.
Quite simply, once you have prepared yourself to deal with the absolute worse case scenario, everything else is a piece of cake.
The Power of Negative Thinking | Wall Street Journal