Exercise is good for long-term health
Most children do not exercise enough to keep themselves healthy and prevent obesity, a government survey shows.
The finding is based on more than 260,000 people in England who responded to the Change4Life campaign poll.
The results showed nearly three-quarters (72%) of children do not take part in the recommended hour of daily activity outside school.
Change4Life was launched in January to tackle soaring rates of obesity by promoting healthy eating and exercise.
Children and young people should achieve a total of at least 60 minutes of at least moderate intensity physical activity each day
At least twice a week this should include activities to improve bone health, muscle strength and flexibility
Activity can either be all in one go, or through several shorter bursts
Its latest poll also found 45% of youngsters watched TV or played non-active video games before school.
Only 22% did something active after their evening meal.
Public Health Minister Dawn Primarolo said: "Our survey shows that kids just aren't getting up and about as much as they should.
"If we're going to cut obesity levels our children need to be active for at least 60 minutes a day.
"By eating better and moving more, we can all live longer and healthier lives."
Tam Fry, of the National Obesity Forum, said he was not at all surprised by the findings.
He said: "Children are more dedicated to sitting in their room playing on their computers and watching television than taking exercise.
"Unless we do something to make play more enjoyable then they are not going to get the balance right between energy going in and energy going out.
"However, it is a huge challenge to come up with ways to make physical activity more fun, something that children's imaginations can latch on to."
Mr Fry said it was not acceptable to expect children simply to go down to their local park, when in many instances they were run down, and potentially unsafe.
He said concerted action was required to provide children with stimulating places where they would want to take exercise.
Dr Ian Campbell, medical director of the charity Weight Concern, said it was vital that parents led by example.
"More exercise benefits us all. For most children obesity is entirely preventable and an active life starts at home. Or preferably in the garden."
Change4Life is launching a new advert aimed at encouraging families to work together to improve their lifestyles.
It stresses that inactivity can lead to a build up of fat which has been implicated in diseases such as type 2 diabetes, cancer and heart disease.
As part of the campaign, families have been sent support packs designed to help them make changes to their daily routine.