Prepare for this 20-minute AMRAP (As Many Rounds As Possible) circuit with a comprehensive warm-up that activates your entire body. Focus on dynamic stretches for the shoulders and hips, and include movements like arm circles, leg swings, and a brief session of jumping jacks or jump rope to get the heart rate up. For the pull-ups, aim for a strong, controlled motion, using a band for assistance if needed to maintain form and volume. The air squats should be performed with depth and precision, ensuring full range of motion for maximum benefit. If 40 in a row becomes challenging, break them into smaller sets to maintain consistency and form. When tackling the 80 double-unders, focus on keeping your jumps minimal and wrists flicking efficiently. If double-unders are not yet in your skill set, substitute with single-unders at a 2:1 ratio or practice attempts mixed with single-unders to keep the intensity high. Cool down with static stretches targeting the shoulders, quads, and calves. This workout emphasizes cardiovascular endurance, lower body strength, and agility, so pace yourself to stay consistent and efficient across the 20 minutes.