Psychological release for me is escape from the physical and mental pressures of incessant work and the headaches and fatigue that arise from it.

Escape takes different forms. One is music, and musical tastes have both stayed and developed, with jazz now jockeying with the Romantic repertoire and chamber music joining the concerto. But as I often work while listening, music does not mark true release.

Another is the escape that comes from taking a hot bath. Over the years, I have taken different paths at bath time - marking essays, or writing, or making notes - but part of the luxury of a misspent middle age is to turn to the comfort blanket of reading a detective novel, soaking in very hot water, in a room where no one can get at me and time seems to hang still in the air with the steam. While we're on the subject, I also like bath oils - but the key element is hot water. I like to leave the bath heated to a pink.

Then there are the pleasures of the great outdoors: the remoteness of walking as if above the landscape, and watching the refraction of light on water, sparkling into the air, are both experiences I have sought to recapture since childhood.

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Exeter is a city of more than 120,000 people, with bustling streets and busy roads - increasingly crowded and busy - but the city vanishes surprisingly quickly into the folds of the hills, especially, but not only, to the north. There are several vantage points from which the walker can look down and out on to more hills; down the Exe estuary to the sea; east to Woodbury Common, surprisingly high above the estuary, and beyond to the Sidmouth Gap to the east; or the Haldon Hills, cut off at the same height as if by a master potter, to the southwest.

Raise your eyes beyond the hills near Posbury and, through the smoky light of low cloud, you can catch glimpses of Dartmoor. In the burnt light of a late afternoon in summer, the tors are picked up, while Cosdon Hill looms into clear view. From Woodbury Common, the coast is spread out in a theatre of nature, clear in the foreground at Budleigh Salterton and Exmouth, and blending into sky and sea in the distant vision across Torbay to one side and toward Portland on the other.

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The walker as observer: the art of nature endlessly varying in the frames of sky and horizon helps me to forget myself and to keep anxieties at bay. The endlessly variable nature of the Devon weather (if you don't like it, wait half an hour and it will be different) makes views shift, swept aside by wind or dissolving into cloud; and that accentuates the variety of vistas.

There is an incessant changeableness I never experienced when I taught at Durham and lived in the North East, although the cold, clear mornings of winter there brought a sharpness of image that could be euphoric.

On the whole, however, I have come to prefer a smokiness of natural light sliced by sunlight. I recently found that at the Eastern Continental Divide near Boone, in the Blue Ridge Mountains of North Carolina, and indeed one of the pleasures of visiting the US is the combination of vistas and light. The walking at height can be amazing, and I have lately enjoyed some fine walks in North Georgia. There is much to be said for walks that plunge you into the almost painfully bright sparkle of light on water. To walk alongside the Chesapeake - the largest estuary in the US - or the waters that feed it, such as the James, is to be taken back to childhood pleasures. However, I have jumped from paddling water when told of nearby water moccasin snakes.

The same (pleasures, not snakes) is true of Devon coastal walks, notably from Beer to Branscombe, or west of Lyme Regis - where you can almost imagine a dinosaur appearing - or river walks with Sarah, my wife, such as along the Teign below Castle Drogo: the south side of the river is better and less popular; and you can head up the slopes to the Iron Age fort above and look down on the castle. Light on the water has its own flow, born of the water but moving on its own, alike but different to light on the eye.

I would recommend Raddon Hills for the best views from near Exeter towards the moor, but the crest northeast of Silverton, unnamed on the Ordnance Survey map I use to plan views, gives fine prospects not only south to the sea but also north to Exmoor. Coming down the steep slope across Yarde Down, you enter the landscape you have just been viewing: you are swallowed by the prospect. You can also feel the wind and sense the change in the weather across your body. Although the climate was a big item in my geography A level, I never really understood the idea of a cold front until I faced a banked-up southwesterly on Raddon Hills. It is a big pity that the crest westwards is blocked, but part of the interest of the landscape is to imagine views you are not allowed to see.

The students, of course, fail to spend enough time in the countryside, which leaves it to old farts like me. I feel that I have come full circle. Favoured moments of childhood were walking Rufus, the successive name of two dogs (my father had a patchy memory). At least a pet always understands the child. Now maturity seems to mean not needing a dog as a companion.

I do not generally enjoy my own company, but do when walking, feeling part of the landscape. On my own, my favourite walk is from Blackdown Cross, southwest of Crediton along the lanes to Fivegate Cross. I then generally climb the gate and walk down towards Great Harford. It is not a public right of way but, if challenged, I know a local who will vouch for me and the views south are amazing. Then back along the lanes to Merrymeet, east, sometimes trespassing into Meetford Wood (careful to make sure they are not shooting), down into the Culver valley, across the river, up the lanes to Oldridge, and back that way or via Tomhead Cross and the lane through Combe Brake.

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Every step brings a new view, memories of past occasions and the possibilities of the new. I did that walk on 11 November last year and stood meditatively with some cattle while the Remembrance guns spoke across the valley from Crediton.

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However, I usually walk in company. I prefer that, conversation flowing or not. As I like walks that are fairly arduous, conversations usually pause when going uphill (a common occurrence), and I like to enjoy the view in quietness, but going down the slopes seems to make the conversation flow. I prefer to talk about something constructive, and tend to dislike gossip and academic politics as topics. Some fellow walkers, such as Susan Hayward, a retired Exeter academic, are far fitter than me, but on the whole, I plod along quite contentedly and manage to cope.

Most walks last one to two hours, as they have to fit into the working day, but I prefer them to be longer. Lunch is part of the planning; the weather does not always encourage stops, however. Snacks that can cope with being jumbled along are fine, with Scotch eggs a favourite, and I often like to walk before or after a pub lunch. Although there are superb beers available, my standard drink is a pint of lime juice and soda water.

I try to go walking at least once on the weekend and twice during the week, but a lot depends on weather and season. I adapt some from guidebooks - recently from Culmstock across the River Culm and up on to Blackdown Common - but mostly I just create from the map.

Walking brings the cyclical theme as the seasons recur, striking in difference yet reassuring in routine. How much will the Exe be in spate this year at Brampford Speke? Alongside rebirth there is also the melancholy of change. At Brampford Speke, the railway is no more and common land is being enclosed. The Bell at Thorverton, the best of pubs there, has gone, and the pub at Cadleigh has closed. But do not push the melancholy too far. The Red Lion Inn at Shobrooke has reopened and is much improved. That acts to encourage walks in and around Shobrooke Park, where the decayed drive looks just right for the cover of a Penguin modern classic.

The stuff of experience, the setting of memories, goes, but maybe that is part of the pleasure as, for a while, we are part of that experience. The sole photo of me in my study shows my friend and former colleague Roger Burt standing with me underneath the wind-sheared tree at the eastern end of Raddon Hills with fields towards Thorverton fading into a late-morning mist down the slope. It is at once a solid thing, and yet an account of what I will not be able to do one day. The back is still straight, but I now carry a thumb stick right for my height that Sarah bought me, and wear my father's flat cap.

Maybe the landscape helps me to come to terms with all our passing. I certainly think of death in terms of falling off the coastal path near Ladram Bay, the path a route to the sparkling sea far below. I worry more about the infirmity of being unable to walk easily as I age. As it is, my legs are of different lengths, 1 inches apart, and each foot is twisted so the mobility clinic provides me with a complicated array of lifts and insoles.

Walking brings both relief and pain: psychological relief, and the aches and pains of balancing the legs and steadying the feet. Possibly the latter helps to account for a sense of achievement during a walk. And I always write better and with more purpose afterwards.

Walking and reading; habits maintain and hobbies recur. Thinking about history has always been intertwined with my reading and walking. They combine well, and that is important to life.

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