The lung is a pretty simple movement that you've certainly carried out countless times before, but there are a few significant subtleties that you can consider in order to shield yourself from knee injuries further down the track.
100 foot Handstand Walk 100 foot Walking Lunges (2x22.5/15 kg) 6 Ring Muscle-Ups 100 foot Handstand Walk 100 foot Walking Lunges (2x22.5/15 kg) 4 Ring Muscle-Ups 100 foot Handstand Walk 100 foot Walking Lunges (2x22.5/15 kg) 3 Ring Muscle-Ups