The Olympic medal-winning athlete Roger Black will front a government campaign, to be launched this week, to encourage sluggish Britons off their sofas and into an exercise routine.
The keep-fit drive, timed to coincide with new year's resolutions to get fitter, will focus on nine pilot projects, offering everything from free swimming sessions for children outside school hours to organised walks for the over-fifties.
The aim is to make gentle but regular exercise a habit. Ministers will study the outcomes, together with Sport England, to find the most effective way of encouraging Britons to do more sport.
'If we're to tackle the obesity problem it's vital we get the country moving,' said Health Secretary John Reid. 'These projects aim to show people that exercise can be fun and that you don't need to go over the top to get healthy.'
The projects will cover all age groups, but evidence suggests that, after 50, regular exercise can not only reduce heart disease and arthritis but also reduce falls and accidents - common reasons for older people ending up in hospital.
Such campaigns have a chequered history: Baroness Cumberlege was mocked in 1996 for launching a fitness campaign with the admission that she kept active by chasing the bullocks on her farm.
The drive comes amid growing concern at the threat to children's playgrounds, which help encourage youngsters to remain active after school and at weekends.
No reliable statistics are kept on the number of council-owned playgrounds in Britain, but campaigners believe that an increasing number are under threat, particularly in the inner cities, with pressure to develop land for commercial use.
In the borough with the highest rates of obesity, Tower Hamlets, in east London, families are unhappy at the dereliction of the three playgrounds serving their areas.
One of those is in Shacklewell Street, a rubbish-strewn area which residents have tried to have cleared for two years. A local resident, Hester Hettinga, said: 'The council wants to take no responsibility. Only once in that time has it been cleaned up, and now it is like a rubbish dump.'
The National Playing fields Association said this was a common story. Its director, Elsa Davies, said: 'We have seen playgrounds that are positively dangerous.
'It is no good councils closing playing areas and building sports centres if the local centre is two or three miles away. We need lots of open areas, well maintained and well used by families.'
The Department for Culture, Media and Sport will shortly receive a report from Labour MP Frank Dobson on the state of the country's playgrounds and produce its own recommendations.
