i never work out my lower body with weights, the only exercise they get is from the elliptical machine. If i lift with them or even run on the treadmill my knees kill me for around a week, longer if i lift more then 1 day. my doctor said if i didnt lose weight my knees would be worthless in 10 years, so i lost weight, about 60-65 pounds, but my knees still hurt after leg workouts. any suggestions? i really want to do something about this.