Welcome to our Flat-Belly Challenge: 21 days of workouts, belly-blasting tips, and fat-burning recipe ideas to help you feel slimmer and more confident — not matter the season. Today, day one is all about belly-fat-fighting intervals and a debloating smoothie made with pineapple, kale, and blueberries.
Fire-It-Up Interval Workout
Let's begin with the fat-blasting workout. We've created three versions of this treadmill run, along with a printable version of all three levels. If you're new to running, try the Walk/Run plan farther down the page. And if you want to increase the speed, use the Run Faster program.