Weekly exercise into one or two weekend sessions is enough to produce important health benefits, a study suggests.
And being active without managing 150 minutes of moderate activity a week was still enough to reduce the risk of an early death by a third.
Researchers from Loughborough University and the University of Sydney analysed data on the time people spent doing exercise and their health over 18 years.
Compared with those who didn't exercise at all, people who did some kind of physical activity - whether regularly or irregularly - showed a lower risk of dying from cancer and from cardiovascular disease (CVD), which can lead to heart attacks and strokes.
People aged 19-64 should try to do physical activity:
At least 150 minutes of moderate aerobic activity, such as cycling or fast walking every week, and strength exercises (such as lifting weights) on two or more days a week that work all the major muscles
75 minutes of vigorous aerobic activity, such as running or a game of singles tennis every week, and strength exercises on two or more days a week that work all the major muscles
a mix of moderate and vigorous aerobic activity every week, such as two 30-minute runs plus 30 minutes of fast walking, and strength exercises on two or more days a week that work all the major muscles
But extensive research has shown that exercise and a healthy diet can reduce the risk of a range of diseases - such as cancer, heart disease and type-2 diabetes - as well as helping to control weight, blood pressure and reduce symptoms of depression.