Janette Wolf opens books that will make you “think fit”.

It’s a frightening fact, but we are turning into a nation of couch potatoes. Obesity in Britain has more than doubled since 1980, and a survey of over 10,000 primary children showed fat levels in 10-year-olds are nearly a fifth higher than they were 20 years ago.

So how do we stop the rot? Start them young, is the emphatic message from the country that brought us the Jane Fonda Workout and now these two resource books.

In the case of Alice Cary’s Parents’ Guide to Hiking and Camping, this means even breastfeeding is no bar to the great outdoors. Though pitched at adults accompanying their own children, it would still make a marvellous guide for group leaders on a day trip or camping expedition.

It is stuffed with practical suggestions on everything, from putting up tents to dealing with snakebite. It has games, activities, campfire songs and even creative cookery (recipes for toffee apples, toasted marshmallows and a million-and-one ways to cook a potato) to ensure everyone hits the trail smiling.

Most importantly, it encourages children to take responsibility for parts of the trip themselves - first aid, for example, map-reading or cooking - helping to make them more confident and skilled. It mixes good sense with tremendous exuberance and has you wishing for a group of six-year-olds to take yomping up the nearest hillock.

Bev Davison’s Creative Physical Activities is aimed at schools on a shoestring, which should cover just about everybody. Green at heart, it has an endless supply of suggestions for recycling bits and pieces to turn into games props: old jerseys or pinnies make good blindfolds; hula hoops make hurdles; plastic bottles make bowling pins, and so on.

Ms Davison’s enthusiasm is infectious; when she has finished recycling, she sets about reviving the games curriculum. Races and challenges, games to enhance specific skills. There are also some imaginative ideas for fundraising or getting hold of equipment for nothing: carpet squares from a department store; golf tubes from a golf club; kitchen rolls from your friendly school caretaker. Maybe not all her suggestions make the transatlantic crossing, but teachers will find many that do.