If you are looking for a challenging ab workout that doesn't require any equipment, then Pamela Reif's "10 Minute Killer Sixpack" is perfect for you. In this intense workout, Pamela guides you through a series of exercises that target your abs and core muscles. The workout is designed to be super hard and push you to your limits, ensuring maximum effectiveness. So, get ready to sweat and feel the burn as you work towards achieving a strong and defined six-pack with this no-equipment ab workout.