Karin Peters is not the most likely of Boston Marathon and Ironman World Championship qualifiers. A 54-year-old mother of four, she did not participate in any sports while growing up in her native Sweden and started running in 2009 as a way to lose weight. Two years later, she used the low-volume FIRST program to train for a half marathon, and from that moment on she’s been hooked on chasing finish lines.

In 2014, Karin read the book 80/20 Running, which completely changed her approach to training. “I loved it,” she says. “It made so much sense to me.” Later that same year, she completed her debut marathon in 3:32 and qualified for Boston. By then, Karin (who now lives in Ft. Collins, Colorado) had also done a few triathlons, applying the 80/20 approach to her swim and bike training as well as her running. So, when our 80/20 Triathlon plans became available in 2016, it was a no-brainer: She started using them and qualified for Kona not once, not twice, but three times, most recently at Louisville this year.

“I like 80/20 because it gives me permission to take it easy on some days,” Karin says. “I don’t need to go out and hammer every day to get a new PR like I did in the beginning. The easy days are enjoyable and give me the power to nail (most of) my harder workouts. I don’t dread my sprint and hill work anymore, and at 54 I’m still setting PRs. I’ve been injury free—so many people around me are hurt or injured.”

Needless to say, Karin thinks every athlete should give the 80/20 method a try. But she has a word of caution for newbies: “You really need to pay attention until you get used to it. Easy is way easier than you think!”