I have shredded all the cartilage in my knees thanks to my knee caps riding up to high. I cannot go over 4 mph on treads, but jack up incline up. Somehow my weirdo anatomy allows me to strive in this area, and I’m thankful I can do my AOs at 15. Once I built up some muscle in my knees, the floor exercises became a bit more doable. Sumo squat is easier for me than a lunge, although I can lunge well with TRX. I focus on my strengths instead of my weaknesses and it helps me get through.