For example – try this:
30
seconds of intense running
60
seconds of easy jogging
15-20
minutes of total work
Not only will this burn more calories than 30 minutes of minimal exertion jogging, but it will also force your body to burn more calories after stopping. With this type of high intensity training, with incomplete recovery (intervals), you can actually increase your metabolism – not just while you are working out, but for hours after you are finished.
Go the extra mile and push yourself, test your limits. You never know what you can achieve until you push yourself past where you thought imaginable.