A LOT is written about strenuous exercise and the best way to tone the body but what is often overlooked is that the most popular fitness pastime of all is walking.

It has a lot going for it – it is in the fresh air, not a sweaty gym, it is free and many experts regard walking as the most complete form of exercise.

If you are a bit longer in the tooth you don’t feel out of place walking as you might in a gym – and most important of all you can visit some lovely places as well as boosting fitness levels.

The AA has just released some new additions to their 30 Walks in a Box set with each route printed on individual, durable and water-resistant cards so all you need to do is just pop one in your pocket and go.

A selection of walks in Hertfordshire is among the new releases and they are so varied and interesting that I defy even the most determined couch potato not to be tempted out of their armchair on a warm sunny day.

The walks vary in length from two to 10 miles and each has a clearly laid out information panel, demonstrating how hilly or otherwise a walk is and the level of difficulty.

Among the options are four local walks including a seven miler from Markyate to Flamstead which takes walkers on Watling Street returning along a chalky ridge.

Then there is a 5.5-mile walk in Rothamsted Park, Harpenden, which explores the historic town and common before taking in part of Rothamsted Research as well as the park.

A five-mile walk around Wheathampstead looks at the triangle formed by three Roman roads in which the village grew up and guides walkers through Devil’s Dyke to Nomansland Common.

And just down the road is another five-mile walk at Ayot St Lawrence which includes George Bernard Shaw’s house in the village.

The remaining 24 cards take in many beautiful parts of Hertfordshire ranging from Little and Much Hadham and the Beane Valley to Ashridge Park, Aldbury and Sarratt nearer to home.

Each card has a map on the front and points out places of interest along the way.

For the more adventurous walker, a new guide entitled Britain and Ireland’s Best Wild Places pinpoints areas renowned for their untamed treasures.

Packed with 500 journeys across the country exploring storm-battered headlands, hidden waterfalls, tumbledown cottages, haunted chapels and old mines and quarries, it introduces keen walkers to some fascinating places in Hertfordshire which they might otherwise be unaware of.

One such is Minsden Chapel in Hitchin which once refreshed and revived medieval pilgrims en route for St Albans Abbey. Now a ruin it is screened by trees but a wealth of stories have built up around it.

Another such is Frithsden Beeches, a range of old trees on the ridge above Berkhamsted some of which could be as old as 400 years.

The guide which includes Ordnance Survey grid references and a list of symbols which helps to list sites of special interest is the work of Christopher Somerville who has spent a quarter of a century walking the country lanes, back hills and wildernesses of Britain and Ireland .

He is the author of Coast and Coast: The Journey Continues which accompanied the BBC2 series and writes regularly on country walks for such publications as the Daily Telegraph.

30 Walks in a Box is available for �6.99 from theAA.com/shop and Britain and Ireland’s Best Wild Places is published by Penguin and costs �19.99.