The amount of time we spend exercising and keeping fit has fallen due to the time we spend doing other activities such as surfing the net, playing on computers and watching more television. It is good to relax and enjoy these activities but it is very important to remain active doing other exercise.
Most young people are physically active for half an hour a day, this sounds like it is a lot but its not good enough to benefit you health-wise and keep you feeling fit. To achieve a fit and healthy body you should be doing AT LEAST 1 HOURof physical activity a day, this doesn't mean pushing yourself to the limit. You don't need to go to a Gym or Fitness Centre (although they can be fun) you could try one of these:
Light Jog
Cycling
Brisk walking (setting off to school earlier and taking the long route)
All of these will benefit you, as long as the exercise makes you slightly warm and slightly out of breath you will be hitting the target and on your way to a healthier body.