The principles of this program can be personalized to fit every person's needs. You don't have to do exactly the same weight Kris Gethin is doing in order to get a great workout. Your body will respond in its own way to this immensely difficult program. As long as you're putting in the effort and eating the right food at the right time, this trainer will work.
By now, you might be wondering why you're continuing to do cardio in this muscle-building trainer. Gethin prescribes it because, first of all, you need to keep your heart healthy. It is a muscle, after all, and it needs exercise just like any other. Second, although this is a muscle-building trainer, the goal is to stay lean. Gethin wants aesthetic muscle that looks great and isn't just sheer bulk.
Follow his lead and knock your cardio out of the park.