There should be more PE in primary - with teachers given the specialist support to deliver it - and more competition to make pupils more resilient, according to Judy Murray.
The tennis coach, captain of the GB women's team and mother of the British men's number one and US Open champion Andy Murray, called on parents to play their part in ensuring their children were active.
She played ball games with sons Andy and Jamie as soon as they were able to walk; this had given them the foundation to play any sport competently, she said. This experience formed the basis of the Murrays' Set 4 Sport physical literacy programme.
Children today were less coordinated and more overweight, said Ms Murray.
"It's difficult for a teacher to do any kind of quality physical activity with 30 kids in their class," she added. "It's easier when they are sitting behind desks in a controlled environment, but when they start running around it's a whole different ball game. We need more specialist PE support to develop that physical literacy in school."
After-school activities also needed to become more widespread and more school teams created, she said.
Some tennis players dropped out, not because they were not good enough, but because they were not resilient enough, she explained. More competition in schools would help address this problem.
"Life is competitive, therefore it's important to understand how to compete."
The key to motivating young people was fun and developing a team spirit, she told delegates at the European School Heads Association conference in Edinburgh.
Earlier this year she accompanied five junior girls to the USA to play a match against their American hosts. Based on their first day of practice she thought they would get "whipped". But by concentrating on fun activities that brought the girls together - such as three-a-side games and painting their nails - they became "a little unit" and beat the US team.
"We weren't going to make their tennis 100 per cent better in three days, but we could influence their thinking."