
Why? Because overall, physical inactivity is estimated to cause 1.9 million deaths and 19 million Disability Adjusted Life Years globally. In the UK, the proportion of deaths attributed to physical inactivity in men and women is about 5-8%.
Three in every four people in the UK population aren't active enough to protect themselves against illness such as heart disease, stroke, diabetes and some cancers.
At least

All young people (5-18 year olds) should participate in at least one hour’s moderate intensity activity each day.
Those who do little activity should first aim towards half an hour a day of moderate intensity activity.
At least twice a week, young people should carry out activities to help enhance and maintain muscular strength, flexibility and bone health. Relevant activities are climbing, skipping, jumping, gymnastics and sports.