Swapping just one hour of sitting with walking or other physical activity each day decreases your chance of an early death by 12 to 14 per cent, according to a University of Sydney study of over 200,000 Australians.
The landmark study, published in the International Journal of Behavioral Nutrition and Physical Activity, is the first to examine the impact of swapping time spent on activities like sitting, standing, sleeping or walking on mortality.
It reveals that swapping even one hour of daily sitting with standing is linked to a five per cent reduction in the risk of premature death.
Lead author Associate Professor Emmanuel Stamatakis from the Faculty of Health Sciences and Charles Perkins Centre said with only 24 hours in each day, the study shows we must choose to spend our time wisely.
"Previous research established the benefits of adequate physical activity or sleep and the risks of too much sitting, but this is the first to look at what happens when we replace one activity with an equal amount of another," said Associate Professor Stamatakis.
"The results show that inactivity is an even bigger public health challenge than we initially thought.
"With the average person sitting watching two to three hours of TV a day, there is definitely scope for people to get off the couch and be more active.
"But it's also time for governments to realise that physical activity cannot be treated as the sole responsibility of individuals because we live in a physical activity-hostile world.
"Finger-pointing at people because they do not do the right thing has not solved any health problem to date and it is not going to solve the problem of inactivity either."
The study used statistical modelling of health-related data from the over 200,000 randomly sampled middle-aged and older people from New South Wales who took part in the 45 and Up Study over a four year period.
The researchers also found that replacing one hour of sitting with sleeping each day, in those who aren't getting enough sleep, was linked to a six per cent decrease in risk of premature death.
However, risk of an early death was increased by between 13 and 17 per cent when one hour of daily walking or exercise was substituted with equal amounts of sitting or any other sedentary activity.
"The important thing for people to remember is the more you move the better, even if this movement is incidental or at a light intensity," said Associate Professor Stamatakis.
"It doesn't have to be formal exercise in a gym, it can be as simple as kicking a ball with your kids in the backyard, going for a walk in the neighbourhood instead of watching another hour of TV, or walking your dog for an extra half an hour a day.
"But we also need a long-term vision that makes physical activity the easy and convenient option.
"This means better infrastructure like more cycleways, better connected parks, and better public transport so physical activity becomes an integral part of people's daily lives."
The study is led by the University of Sydney in collaboration with University College London, San Diego State University and the National Cancer Institute, USA.