As with any healthy habit, exercise is for life - not just for New Year when you've made that resolution to work off the festive flab.
But the day-to-day reality is that as Britons age, the less they play sport.
And of all the depressing statistics on the subject of fitness and fatness in 21st Century UK, the most alarming is the one which shows the biggest fall in sports participation occurs among school leavers.
In fact, we have one of the sharpest drop-off rates between the ages of 6-11 and 20-24, and one of the lowest adult sporting participation rates, in Europe.
In 2000, only 32% of adults in England were taking 30 minutes of moderate exercise five times a week.
And just 46% were participating in sport more than 12 times a year, compared with 70% in Sweden, 57% in Australia and 80% in Finland (where the participation rates increase with age).
The cost of Britain's physical inactivity is estimated to lead to 54,000 premature deaths, and a medical bill of at least £2bn, every 12 months.
A 10% increase in adult activity would help save 6,000 lives per year and help cut annual NHS costs by £500m.
The good news is the measures put in place by the government do appear to be working - albeit slowly - but how did we allow school sport to get in such a terrible state in the first place?
Part of the problem can be traced to the 1980s, when the long-running teachers' pay dispute saw after-class clubs and inter-school competitions fall by the wayside as new terms of employment dictated teachers' hours and staff worked-to-rule.
By the late 1990s, with the boom in electronic entertainment and lifestyles becoming more sedentary, the UK had become an unfit nation - and the need to rescue school sport was firmly on the political agenda.
In 1997 the government established the first Sports Colleges - secondary schools specialising in PE.
They were quickly judged a success and in April 2000 Labour launched its blueprint for getting the nation's youth switched back on to sport - "A sporting future for all".
Five years into the grand scheme, school sport is receiving unprecedented levels of funding.
In 2000, Blair's administration pledged £2bn over three years. In 2003 they committed a further £459m over a further three years and recently revealed plans to invest an additional £519m between April 2006 and March 2008.
Sports College: Centres of excellence in PE and community sport. 1997: 11. 2005: 328 in England. 2006 target: 400.
School Sports Partnership: Clusters of schools (usually eight secondary and 45 feeder schools) grouped around a Sports College with links to at least five sports clubs. In September 2003 there were 222 partnerships. Each partnership has full-time development manager and £270,000 grant. Each secondary school has a school sports co-ordinator two days a week. Each primary school has a teacher responsible for sport.
PESSCL: The national strategy for PE, School Sport and Club Links, launched in 2002.
In eight years, the number of Sports Colleges in England - an idea borrowed from that archetypal sporting nation Australia - has risen from 11 to 328.
To underline the link between academic success and fitness, their GCSE results show signs of improvement and many are now at the hub of School Sports Partnerships, helping - with the assistance of the Youth Sport Trust - to involve children across ages in exercise.
The initiatives, says the Department for Education and Skills (DfES), will result in 75% of all pupils participating in two hours of PE and school sport (in and outside of the curriculum) by 2006, rising to 85% by 2008.
The long-term target is to create a "behaviourial shift" and get 70% of the population moderately exercising for 30 minutes five times a week.
Meanwhile, the methods for discovering Team GB's stars of tomorrow - and links with sports clubs - are becoming more effective, according to the education watchdog Ofsted.
Around 80% of children leave school capable of swimming 25m and extra-curricular games are once again becoming a key part of school life - thanks to a combination of committed teachers and a move towards more flexible working arrangements for specialist sports staff.
Figures below show schools in partnership set-ups are offering a wide range of activities - but some experts believe the emphasis on traditional team sports within the education system is still too great.
"I feel we are continuing to fail those children that do not really want to take part in team games," Eileen Marchant, of the general secretary of the British Association of Advisers and Lecturers in PE (Baalpe) told BBC Sport.
"I would like to see more opportunity for outdoor and adventure activities, skate boarding and Tai Chi.
"We are concentrating too much on organised activities when the attitude should be 'it doesn't matter what activity you do, just so long as you do something'."
The statistics show that while 97% of schools offer football, other team sports such as rugby (67%) are being played in fewer schools as this ethos is embraced.
Martin Ward, of the Secondary Heads Association, said: "The primary role of school sport is to encourage children to adopt a healthy and active lifestyle beyond the school gates.
"Of course we also want to unearth the Olympic stars of the future, but the duty has to be to the majority and you have to 'sell' them the idea of exercise.
"You also have to listen to what young people want - many are not excited by traditional team games and would rather take a dance lesson or work-out in the gym and we have to accommodate that."
Don Foster, the Liberal Democrat spokesman for culture, media and sport, added: "The evidence is that whatever we are doing in school, it is not turning enough youngsters onto sport so that they grow up to be active adults.
"A survey in my own constituency of Bath suggested we are not introducing children to sports and activities which really interest them - such as dancing and martial arts."
It is hoped the change of emphasis will make sport less of a turn-off for girls and ethnic minorities.
Women in the UK are 19% less likely to take part in some sport than men and only 10% of women are members of a sports club for the purpose of playing sport - compared with 22% of men.
And ethnic minority participation is also six per cent lower than the national average.
But if elite sport is used as a barometer of grassroots success, Britain appears to be starting to get it right.
Thanks in large part to Lottery funding, Team GB's 28-medal haul at the Sydney Olympics was the best since 1920. And of the 51 medal winners, 20 were women.
There was also a first individual medal for a British-born Pakistani in the shape of Bolton's Amir Khan.
Based on an index of success in more than 760 sports across 200 countries, the UK was also ranked the third-most successful nation behind America and Australia in 2002.
And though Ofsted says Sports Colleges work well for high-fliers but that not enough is being done to unearth hidden sporting talent among under-achievers, the signs are that the tide is at least turning.