HIIT workouts and weight circuits are awesome for toning and torching calories. But it's also important to get your cardio in! Here is a killer treadmill workout I created that consists of several short sprints that jack the heart rate up, and burn calories quickly. This treadmill workout is a great way to spice up your usual workout routine - especially during the winter when running outside is daunting or very difficult. The workout only takes 25 minutes, and alternates between brisk walking, and sprinting. I highly recommend using a heart rate monitor. It is an awesome tool that allows you to make sure you are getting the best results out of your workouts. I'm obsessed with using my polar heart rate monitor. I programmed my age, sex, height, and weight, which lets me get a pretty accurate reading of my total calories burned after every workout! Nothing beats seeing that I burned over 350 calories in just 25 minutes!