Health experts said that walking or cycling gently has massive long-term benefits.

According to the World Health Organisation, research carried out in Britain and Denmark shows that gentle work-outs and even housework can boost life spans by as much as five years.

The news will provide encouragement for millions of couch potatoes to start taking exercise.

Britain is in the grip of an obesity epidemic, with just 35% of men and 24% of women taking regular exercise.

"Encouraging people to be physically active every day has so many health benefits," said Dr Marc Danzon, WHO regional director for Europe.

"These include reducing the risk of developing certain diseases and of becoming obese, as well as contributing to physical co-ordination, balance, strength and mental well-being.

"It is a very cost-effective public health tool."

The organisation is so concerned that the public is not getting the message on exercise that it will launch a "Move For Health" campaign to boost public awareness.

"The WHO encourages adults to take at least 30 minutes of moderate physical exercise a day, defined as any body movement that results in energy expenditure," said Dr Danzon.

This includes walking, cycling, playing, housework, climbing stairs as well as sports.

He added that children should take at least 60 minutes of exercise every day.