Katie Ledecky shows off her gold medal after winning the 800m freestyle during the Olympic Games in Rio De Janeiro on Aug. 12. (Jonathan Newton/The Washington Post)

LAST WEEK, Ashley Feinberg, a writer at the website Deadspin and a prolific social media user, dug up and retweeted messages various Americans had sent out at the end of 2015. “2015 was the worst year 2016 cannot get worse,” read one. “I’m so ready for 2016 man I’m so over 2015,” read another.

“Little did they know,” the point appeared to be.

Indeed, little did they know that 2016 would see median wages rise while poverty fell at one of the fastest rates since 1959. The economy ended 2016 with an increasingly healthy employment picture, a Federal Reserve confident enough to raise interest rates and a booming stock market. Following a devastating financial crisis, the economy has healed.

And little did they know that, in a year dominated by narratives of racial strife — and after several years of scorched-earth partisan attacks on him — the nation’s first black president would end his second term with high approval ratings and as the most admired man in America, according to Gallup, beating President-elect Donald Trump by a wide margin.

The summer brought triumph after triumph for the U.S. Olympic team, including a dominating performance by the women’s gymnastic squad and the inspiring story of Maryland natives Michael Phelps, who closed out his Olympic career with a slew of medals, and Katie Ledecky, who collected a pile of her own. No offense to Mr. Phelps, but we hope he is someday known as the male Katie Ledecky.

Climate scientists continued to sound the alarm on global warming, but the world formally adopted the Paris climate agreement in 2016, a signal achievement that Mr. Trump seems less likely to undermine now than a few months ago. There were a variety of lesser-known environmental triumphs, too. After years of effort, international negotiators finally agreed to phase out hydrofluorocarbons (HFCs), potent greenhouse gases, in a smart compromise deal. A group of nations that included the United States, China and Russia also agreed to protect a vast swath of pristine, life-supporting ocean off Antarctica.

Obesity and drug use continued to threaten Americans’ health, but years of investment in medical research also paid off. Medical breakthroughs, particularly the use of immunotherapy and precision medicine in cancer treatment, became increasingly mainstream, helping to drive a drop in the death rate from one of mankind’s greatest killers.

The year ended with a controversial and surprising presidential election — but also a reaffirmation of the peaceful transition of power on which this country was founded. President Obama and Mr. Trump could not be more different. Yet no one doubts who will be in the Oval Office on Jan 21. That should be awe-inspiring.

The real lesson Ms. Feinberg’s retweets tell is that people are often bad at evaluating the present and predicting the future. Pessimism and cynicism are, in fact, irrational responses to a year that brought real lows — but also much to be thankful about. By the same token, while 2017 will undoubtedly require men and women of good faith to behave with care and vigilance, it very likely will not be the nightmare the doomsayers anticipate.