PopsugarFitnessWorkouts15-Minute Cardio Bodyweight WorkoutIf You Only Have 15 Minutes to Exercise, This Bodyweight Cardio Workout Is All You Need January 8, 2020 by Jenny Sugar View On One Page Photo 5 of 5 ADVERTISEMENT () Start Slideshow Share This LinkCopy ← Use Arrow Keys → 5 High Knees Run in place while lifting your knees high to the level of your waist. Engage your abs as the knee comes up.Pump your arms to warm up your upper body. Do 40 seconds of high knees followed by a 20-second rest.PreviousNext Start Slideshow WorkoutsBodyweight ExercisesIntermediate Workouts15-Minute Workouts