This 'J-Core' is great. You workout with one of the DVD's for 20mins each day. That may not sound like much, but I'm a 160lb 30y/o man who lives a pretty active lifestyle and I can't keep up with it yet! These are all simple activities that we just never do. The workouts are short, efficient, and fun. makes me smile and laugh a little bit. Any first-timers, even if you are physically fit, I promise, you will feel it in every muscle in your body! No weights? YOU are the weights. BTW, I saw first the Ad for the book version of your workout 'Cardio Core 4x4' in 'Bicycle' magazine. For me, the book was hard to use, but at least I could see what your system was all about, and it does contain alot of good reading material that you don't get from the DVD's. I am very happy with the J-Core workout DVD's. More than worth the money! But Jay, you should've still named it 'Cardio Core 4x4' like your book(that name got my attention in the first place). Thanks Jay, for producing this workout, and for being a fun instructor. Matthew Z in Tampa Bay, Fl.