One small step... Inactivity is world's fourth-biggest killer

A quarter of British adults now walk for less than nine minutes a day – including time spent getting to the car, work and the shops. The figures, from a YouGov poll for the Ramblers, published exclusively in The Independent on Sunday, reveal that a quarter of Britons walk on average for less than an hour every week.

The survey of more than 2,000 over-18s shows that while nine out of 10 Britons agree that walking is a good form of exercise which can keep you healthy, most are not doing so nearly enough.

Almost half of people surveyed walk for two hours or less a week – meaning they are not doing enough walking to stay healthy. Chief medical officers recommend that adults do 150 minutes of moderate physical activity, like walking, per week, but 43 per cent of people surveyed walk for 120 minutes or less.

William Bird, a GP who specialises in the benefits of exercise, said: "We're going to find this generation will die earlier than their parents if they don't start doing basic movement. We all age quicker when we're not moving and the consequences of that are age-related diseases, such as diabetes, cardiovascular disease and cancer."

Dr Bird trains other doctors in the importance of telling their patients to move and said the figures should be a warning to his colleagues to make encouraging exercise a priority. "A lot of doctors know very little at all about the importance of physical activity and it's at the bottom of their list, but if you got everyone walking it would have a massive effect on the health of the country."

Two-thirds of adults in the UK are not doing enough physical activity for good health and the World Health Organisation now ranks physical inactivity as the fourth-biggest killer in the world – ahead of obesity and just behind high blood pressure, tobacco and high blood glucose. The British walking charity, the Ramblers, is calling for a "walking revolution" to get 100,000 more Britons on their feet and going for regular strolls as part of their daily lives. Their poll was commissioned to mark the start of Get Walking Week, when Ramblers groups across Britain will be leading free short walks of five miles or less led by experienced walk leaders.

Benedict Southworth, chief executive of the Ramblers, said: "We want people all over Britain to join the walking revolution and take their first steps towards a healthier and happier lifestyle. Walking is one of the most accessible and achievable ways to conquer this inactivity pandemic in Britain, and we need to get started now. Find a short walk with your local Walking for Health scheme or Ramblers group during Get Walking Week and join us as we get Britain moving."

Diane Abbott, Labour's spokesperson for public health, said the figures were a "worrying" indication of the state of the nation's health. "If the average person is so inactive then that means that most children aren't seeing adults being active, which will only contribute to the obesity epidemic. One of the ways you can support people to get more active is through public health education, which is why it's so worrying that the Government is cutting that budget."

Ms Abbott believes practical design changes could also improve the amount of walking built into the average Briton's day.

She said: "We need to plan activity into the way buildings are designed. The first thing you see in a building is often a lift – then you have to look for the stairs. It should be the other way around."

Anna Soubry, minister for Public Health, attended one of the Ramblers' walks yesterday at Attenborough Nature Centre in Beeston, Nottinghamshire. She insisted the Government was not cutting public health spending, and had increased the budget given to local authorities for it by up to 10 per cent. But the Government has cut spending on public service advertising – one of the most common routes to raising awareness of the health benefits of exercise.

The annual budget for Change 4 Life, the anti-obesity advertising campaign with animated Plasticine figures, was cut from £25m to £14m in 2011/12. Ms Soubry said: "We have to look – and that's what we're doing – at how we help people to lead the sort of lifestyles that mean they will have longer, happier lives."

Kam Marwaha, 28, from east London, joined one of the many walks held around the country yesterday. Two years ago, the charity worker weighed 13.5st and walked for only 10 minutes a day. Since then, she has lost around four stone through walking and healthier eating.

She said: "Two years ago, my sister suggested doing a charity walk and so I started walking the three miles to work and three miles back. I went from a size 14-16 to a size 8-10."