More than 20million people in Britain are classified as lazy, according to new research.
And almost half of all adults in the north west are officially couch potatoes, according to new research.
Millions of adults are failing to meet Government guidelines on exercise and women are 36 per cent more likely to be physically inactive than men, warns the report.
New statistics from the British Heart Foundation (BHF) show the regions of England where people are most physically inactive, with the North West coming out worst as almost half of the adult population - 2.7million adults - are insufficiently active.
The shock report also shows that physical inactivity is high among people who have gone on to suffer cardiac disease.
Three- quarters of people in England, when referred for cardiac rehabilitation after suffering a heart attack or undergoing heart surgery, are considered physically inactive. And in some areas of the UK the figure is as high as 97 per cent.
This evidence shows a sedentary lifestyle, regardless of how physically active you are, is associated with poor health, scientists say.
The BHF estimates that the average man spends a fifth of their lifetime sitting - the equivalent of 78 days each year - and for women the figure is around 74 days a year.
More than five million deaths worldwide are attributed to physical inactivity and in the UK alone it causes one in ten premature deaths from coronary heart disease, plus one in six deaths overall.
Dr Mike Knapton, associate medical director at the British Heart Foundation, said: "Physical inactivity is one of the most significant global health crises of the moment.
"Levels of physical inactivity and sedentary behaviour in the UK remain stubbornly high, and combined these two risk factors present a substantial threat to our cardiovascular health and risk of early death.
"Making physical activity easier and more accessible for all is of paramount importance if we are to reduce the burden of inactivity-related ill health."
The Physical Inactivity and Sedentary Behaviour Report was published alongside the launch of its MyMarathon challenge this year, urging people to kick-start a more active lifestyle to help improve their heart health.
The challenge encourages people of all fitness levels to run the 26.2 miles in their own time over a month, from as little as a mile a day, with money raised helping to fund life saving research to fight heart disease.
Dr Knapton added: "Our MyMarathon challenge is an ideal way for people of all fitness levels to increase their physical activity and improve their heart health.
"Every pound raised will help fund vital research in the fight against heart disease."
Evidence shows keeping physically active can reduce the risk of heart and circulatory disease by as much as 35 per cent and risk of early death by as much as 30 per cent, says the BHF.
More than 30,000 people took part in MyMarathon last year, raising over £1 million for the BHF's research programme.