Being active and living a healthy lifestyle into your seventies can make a huge difference to your life expectancy, a Swedish study suggests.Academics at Sweden's Karolinska Institute analysed the lifestyles of 1,810 people over 75.The findings, on the British Medical Journal website, said men with the healthiest lifestyles lived six years longer, women had five extra years.Experts said it was never too late to start looking after your health.Being sedentary, overweight, a smoker or heavy drinker is bad for health and shortens life expectancy.The researchers said they did not know how big the effect would be after 75, so they followed a group of people for 18 years.Extra yearsThey showed that smokers died a year earlier, but people who quit in middle age were almost as long-lived as those who had never smoked.Swimming, walking and gymnastics increased life expectancy by around two years. People with a rich social circle lived a year and a half longer than those without.Combining figures for healthy, low risk, lifestyles showed men could extend their lives by six years, and women by five years, by adopting the most healthy options.Even after the age of 85, low risk lifestyles prolonged life by four years.Many of these lifestyle decisions will have been made before the 75th birthday so it is unclear how big a difference changes in later years could make.The report's authors said: "Our results suggest that encouraging favourable lifestyle behaviours even at advanced ages may enhance life expectancy."Figures from the Office for National Statistics showed men in the UK could expect to live until the age of 78 and women until 82.Professor of public health at King's College London, Alan Maryon-Davis, said: "These results should put an extra spring in the step of everyone in later life."They provide good evidence that even in your seventies it's not too late to gain an extra few years to enjoy life by keeping active, living healthily and being involved in family and community."Meanwhile Michelle Mitchell, from the charity Age UK, said there was "no doubt" that being active and having a healthy lifestyle would help people to live longer."It's never too early and never too late to make those small changes that can make a big difference," she added.