Research has shown that if a person spends lots of time sitting during the day, they will need to do more than 30 minutes of exercise to counteract this.
A study has found regular exercise increases antibodies after a vaccine and limits the risk of severe illness from infectious diseases by 37%.
The mental and physical health benefits of green spaces have been well documented, but could blue spaces - like canals and rivers - have a similar effect?
Physical activity needs to improve globally - but to do that we need to understand reasons people aren't exercising.
