I have been working out regularly for three years now. I do step and weight lifting five times a week. I moved my workout "room" to our basement which is cement with carpet and padding. Recently I noticed that my knees ache? They are not really hurting during working out but I can "feel" them. I can even feel them sometimes going up and down the stairs. They don't always feel this way and they aren't so intense that I need to quit the stepping during the DVD. I don't know how to describe it as it really isn't painful, just tender. Anyway, I moved all my step aerobics back upstairs so that I am not jumping etc on the cement. Do I need to quit step all together and get an elliptical? Should I lower my weights? I am trying not to panic. I LOVE step and really don't want to quit but I don't want to have to have knee surgery in the future either. I NEED to workout, it is my stress reliever!! What should I do?