This is the bit that really convinced us. Callanetics fans swear by the results.
Trainers say that one hour has the tightening and lifting value of 20 hours of aerobics, and that you can look 10 years younger after only 10 hours (we assume they're talking about your body, not your face!)
In fact, trainers say you can see an effect after the first session, sounds pretty good to us!
So what exactly does it do?
Right, here we go: Callanetics flattens your stomach, firms your legs, lifts and tightens your bottom, banishes saddlebags, improves your posture and helps with knee, back and neck pain. Phew.
It's not actually designed to make you lose weight, but lots and lots of people report dropping dress sizes!