High-intensity interval training helps increase the calories burn, Romero says. “You can combine any high-intensity move with full body exercise.” The routine involves alternating between periods of high- and low-intensity exercise. A typical workout lasts for about 20 to 30 minutes and usually involves a sequence of different exercises (like jumping jacks, squats, or jumping rope) that’s repeated a certain number of times. You can also apply HIIT to different types of cardio workouts like running or cycling.