Working up the occasional sweat while exercising in middle age will help you live longer than just going for a daily stroll, research suggests.
A major study found those who undertook even the odd period of vigorous activity were more likely to avoid an early death than those who stuck to only moderate exercise.
Even those who have heart disease or diabetes would benefit from exercise that makes them puff and sweat, researchers said - although they warned them to consult a doctor first.
The findings call into question NHS guidelines which suggest the recommended weekly 150 minutes of moderate exercise for adults is just as good as 75 minutes of vigorous activity.
The Australian scientists who carried out the study said undertaking any kind of exercise is important - but strenuous exercise is far more beneficial than a gentle walk.
Their results, in the medical journal JAMA Internal Medicine, reveal that mortality rates for those who said less than 30 per cent of their exercise was vigorous, was 9 per cent lower than those who reported doing no vigorous activity.
For those whose exercise routine was vigorous for more than 30 per cent of the time, the rate of mortality was reduced even more, by 13 per cent.
People who carry out vigorous exercise - and break into a sweat - are more likely to avoid an early death than those who undertake only moderate exercise, a study found.
Lead author Dr Klaus Gebel from James Cook University said: 'The benefits of vigorous activity applied to men and women of all ages [studied], and were independent of the total amount of time spent being active.
Each organisation subscribes to the same guidelines, that 150 minutes of gentle exercise each week is as good as 75 minutes of intense running.
'Our research indicates that encouraging vigorous activities may help to avoid preventable deaths at an earlier age.'
Dr Gebel added: 'Our research indicates even small amounts of vigorous activity could help reduce your risk of early death.'
Previous studies indicate that interval training, with short bursts of vigorous effort, is often manageable for older people, including those who are overweight or obese.