I bought the DVD recently, and was a bit disappointed because I have seen all the exercise, and much more at runningtimes.com and runnersworld.com. However, I am starting to like it because the exercises are quite simple and I am starting to appreciate how easy it is to follow the video rather than try to time each exercise yourself. But I am still not sure if they are that useful (been using them for about a month now, twice a week after my easy to medium runs). Anybody who is using the same workout? How long should I try them before I start noticing the effect? Any alternative program for a core workout?