This is a great workout for those who are just getting started with interval training. As soon as you are comfortable with this routine, try repeating it a second time.

Remember, it's time to get comfortable with being uncomfortable!

This workout alternates 90 second sprints with 30 seconds of walking. You will start at a 9 percent incline and decrease it every two minutes. Be sure to warm-up for at least three minutes on a flat road

before you get started!

The treadmill interval includes three circuits of a one-minute jog, a one-minute run, and an all out one-minute sprint. Including your warm-up, you will spend 14 minutes running. For a greater

calorie burn with some strength training, jump right into this full-body workout! Advanced exercisers can repeat these circuits, treadmill and bodyweight exercises, multiple times. Whatever your choice, don't forget to finish with

a cool down for five minutes plus stretching.