As a child growing up in 1970s Norway, with parents who didn’t own a car and loved to hike, Erling Kagge believes one of his first full sentences was: “How much further is it?”

By his late teens, though, he’d begun to embrace his parents’ ethos. “By then, for me, walking wasn’t just getting from A to B,” he says. “It had a value in itself.” So much so that at 27, he walked to the North Pole and, less than three years later, became the first person to walk to the South Pole alone – a 50-day trek with no radio. A year later he climber Everest. Now 25 years on, a father of three and the head of one of Norway’s biggest publishing houses, most of Kagge’s walking is closer to home. He walks two miles to his Oslo office each morning, hikes in the woods at weekends and has spent many evenings exploring every neighbourhood of his city on foot.

Wherever he goes, walking is the way he gets acquainted. He has walked New York City’s sewer and subway system from the Bronx to the ocean because, he says, “It’s interesting to see the city from the inside out.” He took four days to cross LA on foot, a city where car is king and walking so suspicious he was stopped by the police. In Dublin, walking the route taken by Leopold Bloom in James Joyce’s Ulysses deepened his understanding of the book.

When we meet in St James’s Park at 10am on a Monday morning, he has already walked the 2.5 miles from Battersea where he’s staying. Then the two of us set off to walk some more and to talk about his latest book. Walking is a gentle paean to putting one foot in front of the other. Like his previous bestseller, Silence, published in 37 languages, Walking is pocket-sized. In it he weaves his own observations and experiences with those of scientists, poets and philosophers. “I could have written a book about how walking helps your heart, your lungs and how it helps the climate,” says Kagge. “That half is important. But I wanted to focus on the other half – how walking has changed lives, what it does to our thoughts and emotions, and the ways it has made us who we are.”

Kagge starts by remembering his daughter Solveig when she took her first steps. To watch Solveig reach and stumble was to see her becoming herself, he says. Her personality, her interests and impulses were all revealed as she propelled herself forward. While this was happening, Kagge’s grandmother had stopped walking – her worn-out knee replacements could no longer carry her. Though she continued to live a little longer, Kagge remembers the day she took to her bed as the beginning of the end, its own kind of death.

“Walking on two legs,” says Kagge, “laid the foundation for everything our species has become.” It enabled Homo sapiens to travel long distances, hunt in new ways, explore, learn and grow. While we still don’t fully understand the connection between walking and intellect, we’ve always known it’s there. Countless thinkers and creative people have been avid walkers – Socrates, Plato, Aristotle. Darwin walked what he called his “thinking path” twice daily. Dickens walked all over London, three or four hours at a time. Beethoven… Tchaikovsky… Lin-Manuel Miranda – the Hamilton lyrics were written during Sunday walks with his dog.

When we move the body, we also move our thoughts

In 2014, experiments at Stanford University seemed to confirm a causal relationship. People given tasks designed to measure creative thinking repeatedly increased their scores dramatically after taking a walk. “I’ve always known the effect was there, but until I wrote the book, I’ve never bothered about why,” says Kagge. “We think with our entire selves. When we move the body, we also move our thoughts, our emotions, everything frees up and circulates.”

Walking provides just enough diversion to occupy the conscious mind, but sets our subconscious free to roam. Trivial thoughts mingle with important ones, memories sharpen, ideas and insights drift to the surface.

“It’s good to think when you walk, but it’s even better not to,” says Kagge, who prefers to switch his phone off, too. “That’s when you find answers to questions you didn’t even know you had.”

Pace also plays a crucial part. “Speed narrows you down,” says Kagge. “When you run, when you race, you hold your thoughts and emotions at a distance.” He remembers a passage by Milan Kundera that explores this bond. When we want to remember something, we instinctively slow down. When we want to forget or shake a thought away, we pick up the pace.

But Kagge isn’t only concerned with how walking boosts the brain. He believes that seeing a place on foot is the best way to get up close. “You notice the trees and the buildings, but also the people,” he says. “Today, you can live a life in a car and behind a screen, and never see the people who live around you. It’s dangerous. If politicians walked instead of arriving in their nice cars or flying in by helicopter, perhaps they’d make decisions that are more relevant to the people.” He also points out that most revolutions begin with walking – and that sitting down makes us easier to control.

I’m always struck by how little time you save by driving

In today’s world, we choose to sit an awful lot, usually opting for the car or bus or an extra hour on our screens over a walk. “Being busy is like a religion, everything is geared towards saving time, but still a major part of our lives is wasted,” says Kagge. “In Norway, children walk to school, there’s still a hiking culture, but there’s also a big culture of looking at your phone, going online, watching TV and living through other people. It’s pacifying and lonely. Saying that we ‘don’t have time’ to walk is a huge misunderstanding. Most people underestimate how much time they have. Being able to walk is a fantastic chance to live a richer life.”

In fact, Kagge himself is proof that it’s possible to slow to a walking pace yet still achieve more than most mortals. He was a corporate lawyer before leaving to walk the Poles (“I couldn’t go back to it,” he says. “If you’re a successful corporate lawyer, all you get is more corporate law.”) Instead, he founded a publishing company, Kagge Forlag, that grew and grew (it’s the one that produced Norwegian Wood, the surprise Scandi publishing phenomenon about wood stacking). He’s also an avid art collector, studied philosophy at Cambridge and worked in his spare time as a model for Rolex. Clearly no slouch. “As every walker knows, walking helps you get things done,” he promises. “When you move fast to save time, time moves fast, too. I’m always struck by how little time you actually save by driving. When you walk, time stretches.”

It makes no sense, but somehow feels true to me. Three years ago, our family acquired a rescue dog. Until then, I’d often take 40 minutes out of the working day for a bike ride, pounding the pedals before rushing back to my desk, out of breath and empty of thought, to pick up exactly where I’d left off. These days, the dog and I go for a saunter that takes as long as it takes. I’m happier, more balanced and somehow, by the time I’ve returned to my office, no time is lost, my mind has already moved things along.

Strolling with Kagge through the park and across the Thames also feels refreshingly different to the normal kind of interview where you sit face to face. It’s shared, more friendly, more memorable and less transactional – maybe that’s why Steve Jobs preferred “walking meetings” and Silicon Valley is awash with walking trails.

Before he heads off, I ask Kagge if there are any walks he still wants to do. “I have so many ideas boiling over,” he says. “One is that when I arrive in new places, I’ll always walk from the airports to the city, through the outer areas, the suburbs, the buffer zones.” He explains that last year, in Boston, he tried walking to the airport from his hotel. “I’d looked online and it seemed possible, but when you do it, you have the river to cross, then tunnels that are only for cars. In the end, I had to give up. But next time, I’ll try again.”

How enjoyable can an amble through airport traffic be? For Kagge, it’s all exploration, it’s always new and that’s the point. “When you drive, you hardly experience anything,” he explains. “And when you walk you might not experience anything great. But you always experience something.”

Walking: One Step at a Time by Erling Kagge is published by Penguin at £9.99. Or £8.79 at guardianbookshop.com