I was using cardio coach 2x week back in june/july and worked up to running 6miles with volume 8. I had raced a very challenging 5k race in july with a really great time for me anyway and was able to do it without crashing so to speak. anyway after july I got away from doing the cardio coach workouts because I started running with a girl who use to run in track and was faster than me. I thought I will just do these runs with her and that will be my speed/endurance workouts once a week. well I just recently started back with the cardio coach and itrain workouts this past week, just the 30 minute one and they are kicking my butt. I cant believe how badly my endurance is with these workouts. I had worked so hard to complete them at a challenging pace before and really felt they had helped me physically feel stronger with my runs and faster with them as well. I didnt realize how much they helped improve my running. I could kick myself because I have to start all over again. I want to feel good with my runs again and I dont right now. I also had been training for a half so that is why I also kindof got away from doing them. but let me tell you if I get that powerful feeling and endurance with my runs again after doing these once again, I will never quit using them. I will be a forever cardio coach follower for life. just wanted to share how much cardio coach had helped make me a more powerful runner and didnt even know it. I do now though and I wont take them for granted again. I will let you all know if I get back to where I was in july after using these again, I cant wait!