Your personal trainer is onto you. He knows that you are gay and that his gay Clients are not there to transform their bodies but to just perv on him. He has had enough of it today and he knows he is just wasting his own time. He transforms you into a dumbbell to make you useful for something. You can see, hear and taste everything but you cannot talk or move. The perfect punishment for a gay creep. Your usefulness will be keeping him in shape. Nobody else will know. You will be permanently trapped in this new form.