I am a 42 year old female, 5'51/2", 120 lb, size 3, healthy eater, been using Cathe's weight routines for 7 years, active aerobics for 12 years, really enjoy kickboxing, never had children. I'm perfectly fine with every part of my body except the backs of my thighs. I am not able to do hard core leg exercises because my knees are shot (from what, I have no idea) so I modify with ankle weights and do non squatting weighted leg exercises. I am so frustrated that I can seem to make no dent in this area of my body. Any advice is greatly appreciated.