A failure to encourage people to do more exercise is creating a "tsunami of premature deaths" killing 37,000 people a year before their time, MPs have warned.
The all-party parliamentary group on primary care and public health said an "inactivity pandemic" was also costing the NHS £10 billion a year.
It urged local councils to work more closely with pharmacies, schools, employers and sports facilities to get more people taking part in regular activities.
And, after hearing stark warnings from a number of experts in the course of an inquiry, it renewed calls for the appointment of a dedicated public health secretary of state to co-ordinate action at Cabinet level.
Tory co-chair Nick de Bois said the human cost was "clearly too high" after hearing evidence that 17% of premature deaths from conditions such as diabetes, heart disease, stroke and cancers could be attributed to inactivity.
"As adults and our children are increasingly choosing to live sedentary lives, we are facing a tsunami of premature deaths in England ," he said.
"And with the news that our children are now being diagnosed with long-term conditions as a consequence of unhealthy lifestyle choices, there is an urgent need to improve people's physical literacy to ensure our population enjoy good lifelong physical health and mental wellbeing."
Labour co-chair Sir Kevin Barron said: "Local authorities must take the lead to create local environments to support positive behavioural change in their population, to get more people more physically active and more often.
"And it is essential they do this in partnership with local agencies, such as community pharmacists, schools, work places and recreational spaces to offer adults and children a range of opportunities to engage in activity."
"Public health is crucially important and should be discussed at cabinet level with all departments being held to account in measuring the public health impact of their policies and regulations."