It is 7.30am. The sky is a pink-and-gold blur, and the breeze is invigorating. It’s a perfect day to walk from my London home to the source of the River Thames. I’m travelling light – phone, sandwich, water bottle – so I need nothing but a pair of capacious pockets. I have been walking the 185-mile Thames Path National Trail, with my friend Rhiannon, for more than four years. We do it bit by bit, a section at a time. No need to carry a heavy backpack. No need to book a hotel or pitch a tent. No need to use up weeks of precious holiday. No need to fret about whether we may fall out, or whether one of us will prove more ruggedly resilient than the other; nor any of the myriad factors that must be considered when planning a long-distance hike with a companion. And yes, we’re always back in time for a night in our own beds.

These are just some of the practical benefits of hiking a long-distance trail in bite-size chunks, which compensate for the extra time we spend on travelling and logistics. This morning, for example, I must catch a bus, a tube and then a train to get to the point where we finished six months previously. But by 9am I’m at Henley on-Thames, almost exactly as Rhiannon arrives from her Surrey home. We will walk for just over 12 miles, stopping anywhere we fancy – the Stanley Spencer Gallery in Cookham and a Marlow church distracted us on the last stretch – eventually reaching Tilehurst, where we’ll catch different trains home.

Rhiannon and I can go for months without seeing each other, but our Thames walking days are sacrosanct: an opportunity to walk and talk that no other outing offers. On these days, we catch up on all that has happened during the intervening time – births, deaths, marriages, career changes, world affairs; all the “big” topics are picked over, alongside the purging flow of the river.

The appeal of a long-distance trail or a pilgrimage is often said to lie in its sense of immersion, its soothing day-after-day rhythm and the escape this offers from our humdrum lives. Holiday companies and guidebooks encourage us to walk a trail in a single time period, at the weather-appropriate time of year. In fairness, I love walking like this. But, like most people, I have to accommodate work and family commitments that make it difficult to disappear for days (or even weeks) on end. For me, bit-by-bit hikes have been the solution, enabling me to explore dozens of routes, with different people, throughout the year.

I am currently mid-trail on the South Downs Way with my husband, thanks to a year of sporadic daylong walks, often grabbed at the last minute. The 100-mile route from Winchester to Eastbourne follows old routes and droveways along the chalk escarpment and ridges of the South Downs: having started in Eastbourne, East Sussex, we have finally reached Cocking in West Sussex. We’ve loved watching the landscape respond to each season: scoured by spring rain, basking in summer sunshine, aflame with autumn colour and, more recently, glittering beneath winter frost. All this, not to mention the very different views and wildlife, would have been missed had we walked the route in the traditional eight or nine continuous days.

We have yet to spend a night away from our own beds. But as we approach Winchester this may be inevitable, so we’ve earmarked a couple of quirky pubs along the way (micro-hikes lend themselves just as successfully to weekends, but booking places to stay in advance rather dents the spontaneous feel). For now, we’re revelling in the memories of chalk cliffs, fields of orchids, the tiny medieval churches we keep stumbling across and excellent pubs along the way. Walkers need feeding and the Ram Inn at Firle and the Black Horse in Amberley fed us exceptionally well.

I am also halfway along the 28-mile Medway Valley walk, alone, where the constant companionship of the river and the rich array of history – from Tonbridge Castle to ancient bridges – seems to reflect my own journey through life, while reminding me that we’re never truly alone. River routes do this. Not only do they provide a steady supply of people to greet – dog walkers, anglers, kayakers – but the river itself becomes a companion of sorts.

Finally, I’m four days into the King Charles III England Coast Path with my daughter, Saskia, who, as a busy medical student, can rarely manage more than two days at a time. When it’s completed, this path will be 2,700 miles long, and I fully expect it to take the rest of my life: days and weekends snatched from my daughter’s schedule to suit not only her career but my inevitably ageing muscles. As she is studying in Liverpool, we’ve hiked from there to Southport, as well as the sections between Pevensey Bay in East Sussex and Dungeness in Kent that are reachable from London. One day, all being well, we will join them together to make the full coastal path.

And herein lies the true joy of the micro-hike approach to trail-walking with a companion: it binds a relationship over time. The Thames Path typically takes three weeks to walk, but my version with Rhiannon will take more than a decade, becoming part of our ongoing lived experience, a process during which we bring our changed selves repeatedly back to the river, further cementing a lifelong friendship with each section. This also brings a sense of perpetual purpose: we must both remain fit enough to reach the end.

The bit-by-bit method of course presents a few logistical challenges: a couple of preparatory hours spent poring over maps and online timetables, plotting out routes, stations, bus stops and pubs where we can wait if need be. But I treat the ever-longer travel to and from the path as part of the adventure, and the logistical challenges as brain-fuel.

Of course, the most effective brain fuel is the actual walking. A recent study found that people who logged more than 7,500 steps a day were 42% less likely to suffer depressive symptoms. Nor is it just our mental health that benefits from a good yomp: other recent research found that for each additional hour walked, life expectancy can increase by up to 6.3 hours. My calculations suggest, on this basis, that every day I walk might just give me an extra day and a half in which to finish the England Coast Path with my daughter. Either way, there really is no better pastime.

In the UK, we are spoiled for choice with hundreds of distance trails crisscrossing the land. The big hitters are among the best in the world, but let’s not forget the lesser-known routes. From my London desk, and thanks to my Go Jauntly walking app, I already have my eye on the London Outer Orbital Path (Loop), the Wealdway, the Vanguard Way, the Grand Union Canal path, the Green Chain Walk and the Greensand Way. None of these require a backpack, a place to sleep, an ultra-fit companion or extended time off work.

It is a few months later and my phone flashes. It’s a message from Rhiannon, pointing out that the sun is shining and the River Thames is calling. Our next “leg” of the trail will take us to Goring. Or to Pangbourne, if winter has depleted our fitness. I check my map, then the weather forecast (another benefit of spontaneity), before sending my reply: “Tomorrow?”

Annabel Abbs is the author of Windswept: Why Women Walk, which is published by John Murray Press (£10.99). To support the Guardian and Observer, order your copy at guardianbookshop.com. Delivery charges may apply.