Labouring in the wilds of Tayside may not sound like fun but the fresh air and beautiful scenery are a real tonic.
Like its strung-out sister stress, the cherished state of relaxation has a tendency to arrive unannounced. So it was that half-way through a week's manual labour in the foothills of the Scottish highlands I gazed at the fingers of my left hand and was surprised to see lengths of white nail which had grown in place of the usual chewed stumps.

Cheaper than therapy, healthier than a health farm - there's a lot to be said for a National Trust for Scotland Thistle Camp Holiday. Volunteers between 17 and 70 are eligible to pay good money for some hard labour. The age-range on our group spanned 40 years, and the experience varied widely - it included two Duke of Edinburgh's Award scheme participants, a former teacher, a prospective lecturer and a computer flooring installer.

The work which was required in the Pass of Killiecrankie was hard and Thistle Camps are a contradictory experience. Projects take place in beautiful areas of Scotland such as Glencoe, Arran and Kintail, but the labour itself is hard; physical exertion is strenuous, but the end result is an inner calm. There are few better feelings after a hard day's work in the bracing outdoors than a hot shower followed by a cold beer with Miles Davis trumpeting from the stereo.

Work for the week was split between two historic sites owned and managed by the National Trust for Scotland; the Pass of Killiecrankie, just south of Blair Atholl, and the landscaped environs of the Hermitage, just outside Dunkeld. The steep gorge of Killiecrankie owes its narrowness to geology - a sparkling grey mica-schist rock stranded with bands of quartzite which defeated the ice-age glaciers - and was the scene of the battle of 1689 in which the Jacobites defeated the government forces of William III, marching up the gorge from Perth.

In the shaded pass, afternoon strollers trooped past, hopping over the gaping hole we had dug into the footpath in an effort to install a new drain. The day-tripping tourists probably thought we were serving some sort of community service order as picks were swung and shovels pushed with weary grunts.

It's the constructive anarchy that was so appealing. The liberating feeling of throwing around gravel, of excavating a perfectly sound looking footpath until it was instead a heap of rubble, of standing thigh deep in a pool of mud. Never before have I opened the floodgates of a dam draining a pond and, to be frank, being that dirty in public gave me a child-like thrill.

Most satisfying of all was felling trees, the ultimate in rural vandalism. Stunning auburn-leaved beech line both sides of the pass and the sight of such species being unceremoniously terminated worried passers by, many of whom stopped to ask for an explanation.

Thousands of years ago much of Perthshire, like the rest of Scotland, was covered in woodland' less than one per cent of this remains.

Neither beech nor sycamore is a native species and both are very invasive, casting heavy shade that kills ground flora as well as native trees. The idea in woods such as Killiecrankie, designated a site of special scientific interest, is to preserve Scotland's natural woodlands.

As another mighty beech hit the deck it was comforting to be able to quote some statistics. Oak trees can support 284 insect species, willows and birch only slighter fewer. Beech trees sustain just 64, sycamores less than half that number of species.

Steve, a ranger, taught us how to fell properly. The idea is to saw a large notch, known as a bird's mouth, into one side of the trunk. This dictates the direction of the fall and is critical; get it wrong and you have a tree in limbo caught in the branches of its surviving neighbours. Most satisfying of all you get to put your hands on hips and cry "timber" as the tree descends with a crack and a crash. The take-as-you-find domestic arrangement is not to everyone's liking. Our home for the week was in a Boys' Brigade club where sleeping quarters consisted of male and female dormitories. Meals are prepared by the volunteers The only money needed is of the beer variety.

We explored the surrounding region on a day off, a lovely area which even inspired a decent line from the poet William McGonagall, a man famed for the epic dreadfulness of his verse. From the summit of Ben Vrackie ("speckled hill" in Gaelic) there was a long view down to the "beautiful, silvery Tay" as it winds towards the poet's home town of Dundee, and north to the highlands across Loch Rannoch.

On the fast train back to London, I spent the journey cleaning my new white fingernails before watching the sun set with a dreamy grin, one which only began to fade somewhere around Milton Keynes.

Thistle Camps run from late March to early November. Prices range from pounds 35 (pounds 20 concs) for a one-week camp, to pounds 90 (pounds 75 concs) for the three- week camp to Fair Isle. All food, accommodation and equipment is provided as well as some transport. For a copy of the 1999 programme, send an A4 SAE to Thistle Camps, National Trust For Scotland, 5 Charlotte Square, Edinburgh EH2 4DU