I'd been looking for the DVD copy of Kathy's Aerobox video for quite awhile. My VHS copy saw me through several years of fitness obsession until it finally died on me, and I was so sad that I couldn't find it on DVD. Imagine my surprise when I get the Cardio Knockout and find Aerobox hiding on there! Aerobox is a pretty hard workout (and you can't easily modify it to be low-impact), but its broken down into a bunch of segments, so the time actually goes pretty fast. Its a nice way to add some intensity to your workout routine, although I wouldn't recommend it if you have bad knees and joints.The kickboxing workout is great too, but nothing can take the place of Aerobox in my heart.