That's what Karl Pillemer, professor of human development at Cornell University, founder and director of the Cornell Institute for Translational Research on Aging, and author of "30 Lessons for Living: Tried and True Advice from the Wisest Americans" and "30 Lessons for Loving: Advice from the Wisest Americans on Love, Relationships, and Marriage," asked hundreds of older people as part of Cornell University's Legacy Project.
As he writes on Quora, he was unprepared for the answer he so often received: "I wish I hadn't spent so much of my life worrying."
Several years ago, when Pillemer, a world-renowned gerontologist (someone who studies older people), met June Driscoll, a particularly spirited 90-year old woman in a nursing home, she told him, "It's my responsibility to be as happy as I can, right here, today."
That interaction inspired Pillemer to find out how a generation that's experienced the most loss, troubling historical events, and illness could possibly be the happiest and to pass this knowledge down to younger generations.
Pillemer launched the Legacy Project in 2004 and asked more than 1,500 Americans over 65 years of age about the most important lessons they learned over the course of their lives. In"30 Lessons for Living" he refers to his subjects as "the experts" because they hold more tried-and-true wisdom than any self-help book or pundit could possibly offer.
Pillemer writes on Quora that he had expected "big-ticket items" like affairs, bad business deals, or addiction as his experts' biggest regrets.
But over and over again he heard versions of "I would have spent less time worrying" and "I regret that I worried so much about everything."
"I found this lesson from the experts to be surprising," Pillemer writes in "30 Lessons for Living." "Given that they had lived through difficult historical periods and great personal tragedies, I thought they might endorse a certain level of worry."
Instead, Pillemer explains that the experts view time as one of our most precious resources, and worrying about events that may not occur or that we have no control over is an inexcusable waste of this resource.
"The key characteristic of worry, according to scientists who study it, is that it takes place in the absence of actual stressors; that is, we worry when there is actually nothing concrete to worry about," he writes on Quora. "This kind of worry — ruminating about possible bad things that may happen to us or our loved ones — is entirely different from concrete problem solving."
To reduce how much regret we have in a lifetime, the experts suggested increasing the time spent on concrete problem solving and drastically eliminating time spent worrying. They also provided Pillemer with some ways to shift how we think about worry so that we can more readily move past it:
Focus on the short-term rather than the long-term.
"Well, I think that if you worry, and you worry a lot, you have to stop and think to yourself, 'This too will pass.' You just can't go on worrying all the time because it destroys you and life, really. But there's all the times when you think of worrying and you can't help it — then just make yourself stop and think: It doesn't do you any good. You have to put it out of your mind as much as you can at the time. You just have to take one day at a time. It's a good idea to plan ahead if possible, but you can't always do that because things don't always happen the way you were hoping they would happen. So the most important thing is one day at a time." — Eleanor Madison, 102 years old, from "30 Lessons for Living."
Instead of worrying, prepare.
"If you're going to be afraid of something, you really ought to know what it is. At least understand why. Identify it. 'I'm afraid of X.' And sometimes you might have good reason. That's a legitimate concern. And you can plan for it instead of worrying about it." — Joshua Bateman, 74, from "30 Lessons for Living."
Actively work towards acceptance.
"So many things come to your mind. Now, for instance, somebody might hurt your feelings. You're going to get back at him or her — well, just let it be. Push it away. So I started doing that. I found it the most wonderful thing because everybody has uncharitable thoughts. You can't help it. Some people get on your nerves, and that will be there until you die. But when they start, and I find myself thinking, 'Well, now, she shouldn't do that. I should tell her that …' Let it be. Often, before I say anything, I think, "If I did that, then what?" And let it be. Oh, so many times I felt grateful that I did nothing. That lesson has helped me an awful lot." — Sister Clare, a 99-year-old nun, from "30 Lessons for Living."