when I see the Shakeweight at Bed Bath and Beyond , it look like a lot of fun . I buy it , take it home and do the exercise on the dvd . it be fun , yes , and the lady on the dvd have great energy , very inspiring . unfortunately , very shortly after finish the workout , my neck start hurt pretty bad . I give it a few day , and finally have to make a appointment with my chiropractor . he tell I that two of the exercise on the dvd be probably what injure my neck . both exercise hyper-extended my shoulder , and he say unless you be super fit and know what you be do , weight-bearing exercise that hyper-extend you shoulder be a invitation to injury . -lrb- the specific exercise that hurt I be work with the weight behind the head , and the last one on the dvd design to work the shoulder where there be a lot of shoulder rotation . -rrb- I want to like this product , and once I finish healing I might give the other exercise another try before take it back , but I feel I need to warn people . the dvd just do not make it clear enough how a beginner can avoid injury and this really hurt !