Sometimes I exercise with friends via videocall, but when I want to exercise by myself, I often listen to stuff. I like having a mix of things to concentrate on and things I can half-listen to while keeping count of my situps and whatnot. A few longish recommendations you can listen to for free:

How I Built This: an interview podcast about people who started things that became substantial organizations. I particularly remember enjoying the episodes about Dermalogica, Black Entertainment Television, JetBlue Airways, Southwest Airlines, and the Rick Steves travel empire.

Fresh Text: a Christianity podcast "in which Pastor-scholars discuss a scripture passage and swap sermon starter ideas. This weekly podcast is especially (though not exclusively) useful for preachers who follow revised common lectionary." I kind of find it soothing to half-listen to the episodes in which a married couple (the regular host and his wife, who's also a pastor-scholar) nerd out about translations, share reminiscences, and defer generously to each others' interpretations.

BBC audio fiction: I recommend to your attention the hilarious, profoundly moving, elegant three-hour work of art that is the 9th season ("Series 9") of the sketch comedy show John Finnemore's Souvenir Programme. I also laughed and cried at the recent-history musical Magnitsky: the Musical which includes an impressively riveting "how the complicated paperwork con works" scene. In audio! I'm nearly done with a musical adaptation of Rossum's Universal Robots which was funny enough in Part I that I fully did not expect choking up during Part II. I have not yet tried Kafka the Musical starring David Tennant nor Beethoven Can Hear You starring Peter Capaldi. I had a pretty uneven time with Hall of Mirrors, the musical about John Maynard Keynes at the Versailles peace conference following the Great War. It looks like the BBC has a whole ongoing project funding new cerebral audio musicals? My muscles thank them!