Viki:
I personally recommend low impact circuit. You can adjust the intensity to your liking and I believe it only has 3 or 4 interesting ciruits before you plunge into weights only. There are no heavy bar bells on your back but you gain very well toned arms, shoulders, back and it has an awesome ab routine!!! Your legs won't miss out either because the circuits include cardio/leg drills. It's an hour and 5 or so minutes well spent. Your lungs and heart and..... will love you.