Not a jock? Find other ways to fit activity into your day: walk to school, jog up and down the stairs a couple of times before your morning shower, turn off the tube and help your parents in the garden, or take a stroll past your crush's house — anything that gets you moving. Your goal should be to work up to 60 minutes of exercise every day. But everyone has to begin somewhere. It's fine to start out by simply taking a few turns around the block after school and building up your levels of fitness gradually.
For those of you who aren't familiar with HIIT, it involves intervals of high-intensity exercise (such as running at 90% of your max heart rate) followed by low intensity (walking at a moderate pace) or complete rest. This is in sharp contrast to the typical steady-state cardio most people do at a moderate intensity, such as walking on a treadmill at 60-70% of their max heart rate.
Here's something else most people probably don't know: Fidgeting is good for you. It's considered a nonexercise physical activity, and it's an important way to burn energy. You get more health benefits if, in addition to exercising, you are a more fidgety, more active person the rest of the day. This means gesturing while you're talking, tapping your foot, just moving around.