Walking for 20 minutes a day could save 37,000 people a year from dying prematurely of cancer, heart disease and stroke, according to a report.
But one in three people can barely manage to walk for 30 minutes a week â€“ including everyday trips to the shops, work or school.
Just under half of those surveyed walk for two hours or less a week â€“ far below Government guidelines of 150 minutes a week, or 21 minutes a day.
Only one in 20 people in England does enough moderate physical activity such as walking to get the health benefits, says the report from The Ramblers walking charity and Macmillan Cancer Support.
It reviews research into the life-threatening consequences of inactivity, ranging from early death to a greater risk of serious diseases.
The report Walking Works found if everyone in England did enough walking to meet recommended guidelines each year it could prevent 36,815 people dying prematurely, 294,730 cases of diabetes and save 12,061 people going to hospital for emergency treatment of coronary heart disease.
Research suggests being inactive can take three to five years off your life and increase the chances of developing cancer, heart disease or having a stroke by 25-50 per cent.