Walking was once the only way to go. Nomads trekked the savannahs. Drovers created roads by driving cattle to market. Pilgrims made paths from shrine to shrine. Then along came horses and wheels, steam trains and combustion engines, propellers and wings.

Our feet left the ground and something precious was lost. Walking, our way to touch and understand Earth, became a recreational activity, something only some of us do at weekends and on holidays, and as a result, we non-walkers have grown sadder and fatter.

Sometimes we need reminding that walking is a way to change your life. Wild is a new film starring Reese Witherspoon as Cheryl Strayed, a woman who escaped her imploding life and took to the hills. When her mother died, her family broke up and her life became a mess of broken relationships and drugs, Strayed shook herself awake and decided to trek America’s 1,770km Pacific Crest Trail.

In walking alone through the wilderness, wrecking her feet (a regular feature of long-distance walking), carrying the dead weight of everything she needed to survive on her back, she joined an invisible army. Over millennia, thousands, even millions of walkers have headed on foot into nature to understand and transcend the challenge of their daily lives.

“Foot speed was a profoundly different way of moving through the world from my normal modes of travel,” said Strayed. “Miles weren’t things that blazed dully past. They were the sounds of my breath and my feet hitting the trail one step at a time and the click of my ski poles. The Pacific Crest Trail taught me what a mile was. I was humble before each and every one.”

I have a friend whose brother, a very high-powered man, is one of those committed, even obsessed, long-distance walkers. Even when they were children, he would drag my friend and her sister off on gruelling hikes, and when they complained, he would say briskly to every excuse: “Take it in your stride.”

Taking it in your stride is the essence of the supreme challenge of long-distance walking, whatever “it” is. It might be a career change, a major decision, a bereavement, a simple need to escape daily life.

For Sonia Choquette, another American writer and spiritual teacher, “it” was the death of her brother and then her father, a double shock that impacted on and ended her marriage. Her solution was to become a pilgrim on the Camino de Santiago, the ancient pilgrim trail through Spain to Santiago de Compostela.

Her book, Walking Home, conjures up both the physical challenge — bodily pain, wrecked feet (again), rough terrain — and an inward struggle, the slow unpacking of emotional burdens and the emerging of psychological insights that come with nature, exertion and solitude.

“My mind panicked at first,” she said. “But with each step it quieted down. Over the course of the day I was met with every kind of weather there was: rain, sleet and snow, then sun and fog. I was confused. I didn’t know what kind of thoughts I was supposed to have. For a long time, I had no thoughts at all, simply focusing on my breathing and taking one step at a time.”

According to a study on the psychological impact of long-distance walking carried out at the University of Lincoln, this early panic and confusion is universal. Each trek, no matter where, begins as a challenge. Walkers are motivated by a desire to get away from it all, to feel a sense of accomplishment, to relax mentally and to be challenged. They are encouraged by the experience of being close to nature and of solitude and freedom.

You can get this experience much closer to home than California. Pat Kirkbride is a walker and co-author, with Elizabeth Guy, of Ramblers Rewards, a cookery book centred on England’s Coast-to-Coast walk. She also owns the White Hart in Hawes, Wensleydale, which welcomes many walkers on the Pennine Way.

She says there are always points at the start of a walk when “you think, ‘What the heck am I doing?’. But then something kicks in. We had a woman staying here who was walking the whole length of the country and she said how lovely it was, that you left all normal life behind. Up here it’s a huge leisure industry that starts when the clocks go forward.”

I spent Christmas and New Year in the Scottish Borders and the Yorkshire Dales, regions of Britain that are a spaghetti junction of ancient trails. Every signpost points tantalisingly along the Borders and Abbeys path, the Pennine Way, the Coast-to-Coast. Contemplating these signposts and the trails that lead up to the hills sparks the imagination. One solitary human being — me, perhaps — with a backpack and a pair of boots could step off the Tarmac and walk in the footsteps of giants.

My sister-in-law, Patricia Nicholson, a retired head teacher who goes long-distance walking, says that the moment you put the pack on your back and head off, all thoughts of your daily life — work, families — drop away. She has walked St Cuthbert’s Way from her door in the Scottish Borders to Holy Island (Lindisfarne).

“It’s four days’ walk from here and when you get to the sea there’s an old pilgrims’ path over the sands. You take off your boots and splash through the shallows like all those pilgrims before you. We could even hear the seals barking across the water as we walked along.”

For Patricia, it is the camaraderie of the trail that she loves, “meeting up with other walkers at the end of the day and exchanging stories”. Her brother, my former husband, Ken Grant, a busy international health care consultant, wanted the challenge when, to mark his 70th birthday, he took off for the John Muir Trail in California, 380km of wilderness ending at Mount Whitney. But it was the other walkers he encountered who taught him the lesson he needed to learn.

It was not, as it was for Strayed or Choquette, a profound emotional understanding of his life, but the simple and necessary idea of changing pace. “After the first day,” he said, “I was as tired as I’d ever been in my life, and then I ran into some people who’d taken four days to walk the distance I’d done in a day. I realised that if I wanted to enjoy it, I had to slow down.”

For achievement-driven, modern men such as Ken, slowing down is a revolutionary idea. He thought he’d hike the whole John Muir Trail in two weeks, when it usually takes a month. He decided to walk half the trail in two weeks and return another year to complete it. The man who convinced him was a busy ophthalmologist who walks the trail every summer. “Cheaper than psychiatry,” he told Ken, cheerfully, “and safer than psychotic drugs.”

For the malady of modern life, putting one foot in front of the other through wonderful landscapes is the prescription that works. As Clinton Churchill Clarke, creator of the Pacific Crest Trail, once said: “Time in the wilderness provides a lasting curative and civilising value.”

— The Telegraph Group Limited, London 2015