Fartlek is a Swedish term for “speed play.” This informal version of interval training is simple, effective and dare we say … enjoyable? And not just because fartlek is fun to say.

Exercise columnist Gretchen Reynolds is here to vouch for this often-overlooked, decades-old practice. Reynolds, who helped popularize the 7-minute workout, has found that a growing body of research points to the benefits of this approach, even in small doses. According to exercise scientists, it can improve strength, endurance and longevity and may even lower the risk of dementia.

Today’s show was produced by Elana Gordon. It was edited by Maggie Penman. Thanks to Anjuman Ali.

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Today, we revisit one of our favorite episodes from the past year: about the science of how dogs make us calmer, happier — and maybe even more trusting.

If you want more optimistic content on the weekends, let us know at podcasts@washpost.com and maggie.penman@washpost.com – and check out our newsletter.

Today’s show was produced and hosted by Maggie Penman and reported by Kyle Melnick. It was edited by Allison Klein and mixed by Ted Muldoon.

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The cafeteria at Ballard High School during lunch is a loud place. Students are talking and laughing, playing card games and going out to the courtyard for an informal recess. On Fridays, students have started playing bingo.

It’s a big change from the past couple of years — and it’s not the only one. In the first month of school this year, students took out 67 percent more books from the school library than the same month last year.

Today on the show, we interview psychologist Jean Twenge, author of the new book “10 Rules for Raising Kids in a High-Tech World.”

Listen to our episode about the young people giving up their smartphones.

Today’s show was produced by Maggie Penman and Rennie Svirnovskiy, who also mixed the show. It was edited by Allison Klein.

Subscribe to The Optimist here. And if you want more optimistic stories in your podcast feed, write to us at podcasts@washpost.com.

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