If there is one thing that ought to need no intervention by the government it is getting people to walk more. It should be self-evident. Walking is enjoyable in itself and it is well proven that moderate exercise reduces the risk of obesity, stress, heart disease, strokes and other illnesses. And if that isn't convincing enough then the prospect of avoiding traffic congestion, pollution, soaring petrol taxes, parking problems and high train fares ought to be. Sadly, this is not the case. As the Department for Transport's action plan, Walking and Cycling, pointed out last week, walking trips - other than for recreational purposes - have been in decline for 20 years. It would not take much to reverse it - just walking 1.25 miles a week more on average - but there is no sign of revival.

The chief medical officer urges us to take at least 30 minutes of physical activity of moderate intensity on at least five days a week. It doesn't have to be walking: anything from cycling to housework would do. But cycling without proper uninterrupted lanes can be dan gerous and not everyone can afford a health club. Walking is easy and more sociable than other forms of exercise. Many would be surprised what little time they lose by walking part of the way to work rather than taking a bus or train once all the delays have been factored in.

With obesity costing the country approaching £10bn a year, putting the country back on its feet would have a self-evident payback. The government says that nearly a quarter of all journeys are a mile or less and 42% are less than two miles. There are lots of things the government can do nationally and locally such as improving pavements, creating more safe routes to schools and making more traffic-free areas (as witness the startling increase in walking generated by new passenger bridges in London and provincial cities). If the UK rediscovered its legs it would reduce pollution, lengthen lives and ease congestion. It is the nearest thing politicians will get to a free lunch. Last week's exercise was no substitute for the national walking strategy that has been promised for 10 years.