Popsugar Fitness Workouts 15-Minute Ab Workout I'm a Trainer, and This Is the Ab Workout I Do For a 6-Pack December 6, 2018 by Tamara Pridgett View On One Page Photo 1 of 8 ADVERTISEMENT () Start Slideshow Share This Link Copy ← Use Arrow Keys → 1 High Knees Hold your hands at waist level. Hop the right knee up toward your hands, then quickly switch legs and hop the left knee up. This counts as one rep. Complete 30 reps. Previous Next Start Slideshow WorkoutsStrength TrainingBodyweight ExercisesBodyweight WorkoutsAb WorkoutsCore ExercisesTrainer Tips15-Minute WorkoutsAb Exercises