In addition to the brilliant lecture above, the Wall Street Journal has a great article that reviews why pessimistic thinking is helpful

One pioneer of the “negative path” was the New York psychotherapist Albert Ellis, who died in 2007. He rediscovered a key insight of the Stoic philosophers of ancient Greece and Rome: that sometimes the best way to address an uncertain future is to focus not on the best-case scenario but on the worst.

Seneca the Stoic was a radical on this matter. If you feared losing your wealth, he once advised, “set aside a certain number of days, during which you shall be content with the scantiest and cheapest fare, with coarse and rough dress, saying to yourself the while: ‘Is this the condition that I feared?’ ”

[…]

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.

[…]

Goals may even lead to underachievement. Many New York taxi drivers, one team of economists concluded, make less money in rainy weather than they could because they finish work as soon as they reach their mental target for what constitute a good day’s earnings.

More people are waking up to the fact that positive thinking doesn’t work. It has never worked. Instead, it diverts energy from putting in hard work and transfers it to daydreaming about an outcome that requires much more than just mental thought. Positive thinking is great if you want to set yourself up for one disappointment after another.

Many people tell me that I’m pessimistic, and I take it as a compliment, because it’s that pessimism which has allowed me to accept and endure tough spells in life to push through to the other side. If I didn’t get my mind ready to tackle a big problem, how would I keep my composure to face it? Instead I hope for the best but expect the worst. This old saying perfectly captures how a pessimistic person approaches life.

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