I personally like to do strength on one day and cardio on another. I recently read a comment that Jillian made where she says if you have to do them on the same day to strength training first. Doing cardio tires the muscles and you really can't give strength training your all if you are tired from cardio. If I am trying to burn extra calories and do both in the same day, I do weights first. Jillian also says it is good to do strength training at least 4 days a week and cardio is "extra". I aim for 4 strength training sessions(2 upper, 2 lower) and 3 cardio sessions per week and I add abs in on the cardio days. STS is an awesome weight program, if you don't already have it. I have used it in many ways, worth every peny. Anyway, just my 2 cents!!!