The cover of Peter Sagal’s new book is a Rorschach test of sorts for readers. Those old enough to remember Jim Fixx, the author of the best seller “The Complete Book of Running,” will recognize Sagal’s cover, which pays homage to the 1977 book that introduced many Americans to the joy of jogging.

While it’s too soon to tell if Sagal’s book, “The Incomplete Book of Running,” will have the same impact as Fixx’s classic, it offers readers interesting insights about setting goals, making amends, the human digestive system and life in general.

Peter Sagal’s new book pays homage to Jim Fixx’s 1977 book “The Complete Book of Running.”

Listeners of “Wait Wait . . . Don’t Tell Me!” –– National Public Radio’s news quiz show hosted by Sagal –– will see his wit throughout the book; they’ll also get a glimpse of the pain and sorrow of divorce, something the father of three shares in bits and pieces.

Sagal originally pitched a breezy book about running, but then his life “changed completely within the space of a single year that started and ended with iterations of the same race. It was the most momentous year of my life, and in many ways the worst, but in retrospect it had to be lived,” he writes.

There were two “explosions” that changed the story Sagal ends up telling: 1) The 2013 Boston Marathon, which he ran as a guide for a sight-impaired runner; the pair finished moments before the first bomb went off, and 2) his life, when his marriage of two decades ended.

“It’s not so much about a midlife crisis but a crisis,” he said in a recent interview.

The book is dedicated to his father, who took Sagal at the age of 15 on his first run through their New Jersey neighborhood. He remembers “my orange Keds, slapping against the suburban asphalt for all of a half a mile, and then my lungs exploding. I remember the gentle upward slope of a neighborhood street feeling like K2.”

It didn’t take long, though, for Sagal to start running 10K races and join the cross-country team. He ran off and on through college but largely gave it up until his late 30s when he went for a routine physical and realized he weighed 200 pounds. The doctor didn’t hear his screaming, Sagal writes. “It must have been muffled by all the fat.”

That’s when he began to run seriously, eventually completing 14 marathons and recording his personal record of 3 hours and nine minutes. The book –– part memoir, part advice column –– is both entertaining and poignant.

Sagal recounts his first “Solo Divorced Dad weekend,” which he spent in St. Louis running a charity race wearing only his underwear. He writes about being hit by a car while he trained on his bike for a triathlon; though he missed that race, he managed to recover well enough to complete the Chicago Marathon two months later. And Sagal confides he likely struggled with anorexia as a teen.

He’s not shy about sharing a problem he frequently encounters on his daily runs: the sudden need to poop. So accustomed to dealing with this challenge, Sagal knows the location of every public restroom within four miles of his west suburban Chicago home.

The book has a happy ending of sorts. Sagal, now 53, has remarried. And though he doesn’t run as far or as fast as he once did, on a recent run, as usual, he brought two faithful companions, his dogs Dee Dee and Dutchie, to keep things interesting.

Sagal kept a moderate pace through the streets of his neighborhood; the pace was interrupted only occasionally when the dogs — attached to his waist — spotted a squirrel or stopped to do their business.

He doesn’t run with anything but his dogs – no ear buds, no music.

“I’ve become an evangelist for getting out of your head,” Sagal said later over coffee at a local Starbucks. Pay attention to what’s happening around you, he says. “It all comes back to being mindful. … People shouldn’t think about running as one of those things that is so boring and tedious that you need to distract yourself from it.”

Sagal advises would-be runners to buy nothing. “If you don’t have sneakers, just grab your most comfortable shoes, or go barefoot on dirt or sand. If you don’t have shorts, get an old pair of jeans and cut off the legs.” And stay off those treadmills.

Running offers a number of lessons, he says, like:

1) “The practice of persistence.”

2) “Sometimes it sucks, it sucks a lot … but you can get through things.”

3) “Just keep going.”

Suzanne McBride is chair of the Communication Department at Columbia College Chicago and an editor at the Sun-Times.