Years ago I had the pleasure of following Japan's old Kumano Kodo hiking trail through the Kii Peninsula. This region has long been revered by the Japanese, and the scenic hiking trail doubles as a pilgrim's path that winds from Buddhist temple to Shinto shrine.
Although only 150 kilometres south of Osaka, the peninsula's rugged mountains, dense forest and villages create a real sense of escape from urban stress and life's woes. One of the trail's most scenic sections, between Hosshinmon and Kumano Hongu shrines, passes through glorious cedar forest where meditation logs are laid out under the trees.
You're invited to lie down on a log and contemplate the mysteries of Shinto gods, or simply the beauty of sunlight through branches, for which the Japanese have the word komorebi. It was one of the simplest travel experiences, yet provided a little warp in the time-space of a busy life that I'll long remember.
Of course, there's nothing new in the idea that nature has the power to recharge our spiritual batteries. The Shinto religion, in which gods manifest themselves in rocks, trees and rivers, has been saying so since the eighth century.
Before that, the ancient Greeks built healing sanctuaries on mountains and in olive groves. In the 19th century, tubercular writers settled in the Swiss Alps and inadvertently contributed to the notion of alpine tourism.
As our society becomes more urbanised and indoor-focused, health practitioners are backing up age-old beliefs about nature's power to soothe with scientific research. One of the most recent studies at King's College London in 2018 looked at the effects of being outdoors, seeing trees and sky, and hearing birdsong. The findings showed that short-term exposure to nature had measurable beneficial impacts on mental wellbeing.
Beyond the joys of nature, natural landscapes are also places that invite physical exercise. Modern research also repeatedly demonstrates a close parallel between exercise and mental health, since exercise raises serotonin levels and increases body temperature, both of which elevate mood.
Which brings me back to Japan's forests. The Japanese have another word, shinrin-yoku or ''forest bathing'', for the art of immersing oneself in a forest for wellbeing. This isn't an ancient practice but rather a 1980s fad that has since acquired a steady, worldwide following.
Its leading expert, immunologist Dr Qing Li from Tokyo's Nippon Medical School, has been studying forest bathing for more than a decade, and found that it boosts the immune system, counters depression and anxiety, lowers blood pressure and alleviates stress.
In short, a nature retreat doesn't just provide inspiration and escape from daily pressures, but is demonstrably good for our physical and mental health. Maybe we should get out more, hug a tree or lie on a meditation log. Here's where and how you can get your breath of fresh air.
RHONE VALLEY, SWITZERLAND
THE GREEN PEACE FACTOR: No wonder Romantic poets lauded the spiritual benefits of alpine Switzerland. The Rhone Valley alone is glorious hiking country, with a vast network of signposted trails through flower-filled meadows and beneath 50-odd alpine peaks, guaranteed to make you feel good.
TELL ME MORE: Stay in car-free Riederalp or Bettmeralp and abandon urban stress. You can join alpine yoga, conscious breathing and forest bathing events in ancient pine and larch forest, and even re-energise at supposed energy spots.
DON'T MISS: Aletsch Glacier, a 23-kilometre World Heritage spectacle of rock and ice, especially viewed from Moosfluh or Eggishorn, where you're invited to drop a ''lucky stone'' and symbolically abandon your worries.
LAKE DISTRICT, ENGLAND
THE GREEN PEACE FACTOR: Magnificent peaks, plunging valleys and cloud-reflecting lakes combine to create a beautiful landscape that blends English village cosiness with rugged national park. Barrowdale and Grasmere are glorious valleys, and even popular, much-developed Windermere is spectacular.
TELL ME MORE: William Wordsworth honed his poetic talents in the Lake District and promoted the Romantic notion of rural regeneration, so take to more than 3000 kilometres of rights-of-way around some of England's largest lakes and wax lyrical.
DON'T MISS: Late afternoon at Blea Tarn in Langdale, which reflects lovely views of pikes and fells. Scientific studies show that water views really do promote mental wellbeing, and this place surely provides evidence.
KO BULON LEH, THAILAND
THE GREEN PEACE FACTOR: This small island in the Andaman Sea off Thailand's south-west tip is shaded by casuarina trees, fringed by white-sand beaches and lapped by fish-filled azure waters.
TELL ME MORE: Tropical islands are the epitome of the feel-good, castaway fantasy and yet often distract with busy resorts and cocktail lounges. Bulon Leh has just enough development for comfort without crowds. Explore by walking, snorkelling and soul-searching beneath palm trees.
DON'T MISS: The fabulous beach that wraps around the island's north-east corner, where you can find yourself alone with your thoughts.
DRAKENSBERG, SOUTH AFRICA
THE GREEN PEACE FACTOR: The Drakensberg Mountains run for 1600 kilometres but are most dramatic along the western border of KwaZulu-Natal Province south of Johannesburg. Jagged peaks and tabletop mountains dwarf villages, and every bend in the road is another photo opportunity.
TELL ME MORE: Mountain populations everywhere are healthier than lowland ones, so access some of the goodness and give yourself a workout amid jagged peaks and some of the world's highest waterfalls.
DON'T MISS: Royal Natal National Park, where waterfalls tumble over the escarpment, framed by mountains. This stunning wilderness is available to everyone, with walks meandering below dramatic peaks.
THE GREEN PEACE FACTOR: We all know beaches make us feel good, but they don't have to be sunny or serene. Forest-fringed Tofino on Vancouver Island's battered west coast is Canada's storm-watching capital, where visitors hope for foul weather.
TELL ME MORE: Storm-tossed forest, huge Atlantic breakers, moody skies and winter winds combine in an exhilarating, cheek-reddening display of nature. Rug up and venture out onto beaches pounded by waves and littered with driftwood.
DON'T MISS: A boat excursion to Hot Springs Cove in Clayoquot Sound, where you can sit under hot cascades traditionally used for healing by First Nations people, and watch the snow falling between the branches of old-growth forest.
THE HOT SPRINGS
THE GREEN PEACE FACTOR: Limestone deposits oozing down a hillside have created a series of spectacular tiered white pools and terraces at Denizli in south-west Turkey. Submerge yourself in the warm, calcium-rich milky water and you'll also be refreshed by views extending to the coast.
TELL ME MORE: The 2000-year-old ruins of Hierapolis are a reminder that hot springs have always been associated with relaxation and rejuvenation. Stay overnight to avoid day trippers and enjoy the further balm provided by lovely sunsets.
DON'T MISS: A swim in the effervescent waters of Sacred Pool, part of Pamukkale Thermal Baths. As you swim, you can see ancient Greek columns submerged below.
THE REMOTE PLACE
WUTAI MOUNTAINS, CHINA
THE GREEN PEACE FACTOR: Five peaks of more than 3000 metres provide a backdrop to this Shanxi Province pilgrim destination dotted with temples and monasteries. Buddhists say renouncing earthly desires lets you glimpse nirvana, and certainly there's something soothing and uplifting about this isolated mountainous region.
TELL ME MORE: Tinkling bells and prayer-muttering Tibetans provide a background murmur to an inspiring landscape of high mountains and wildflowers that provides an exhilarating alternative to China's unrelaxed big-city sights.
DON'T MISS: Taihaui temple complex, centred on a giant white stupa. A 108-step temple staircase represents the 108 earthly worries cast off as you ascend upwards. The view of snow peaks alone is heavenly.
THE TALLEST TREES
REDWOOD FOREST, CALIFORNIA, US
THE GREEN PEACE FACTOR: Northern California's Redwood Forest National Park protects nearly half of America's remaining old-growth redwood forest. The tallest trees on earth have been a source of awe for at least 3000 years, with Native Americans considering they contain powerful spirits.
TELL ME MORE: You can't hug these enormous-diameter trees, but you can take to 320 kilometres of trails amid them. If forest bathing is good for you, this will certainly put a spring in your step.
DON'T MISS: The renowned half-day, uphill hike to Tall Tree Grove, a particularly renowned group of redwoods, many over 100 metres high, made famous by a 1963 National Geographic article.
BLACK FOREST, GERMANY
THE GREEN PEACE FACTOR: This wooded range of hills in south-west Germany features forest mixed with open landscapes of rolling farmland, small lakes and crags, through which roads and hiking trails meander.
TELL ME MORE: Forests have long been seen as mysterious places of refuge, transformation and adventure. You can up the wellness ante by looking out for the ''Schwarzwald Balance'' logo that indicates health-conscious local spa treatments, restaurant menus and beauty products made from elder and spruce.
DON'T MISS: The most recently created of 20 long-distance hiking trails criss-crossing the region, Schluchtensteig, which runs through the southern Black Forest's seven gorges and canyons and offers particularly inspiring views.