"You're looking go-o-od. You're looking go-o-od. You're looking go-o-od." The zumba leader sings her encouragement. Looking at my reflection in the floor-to-ceiling mirror behind her, I think, You lie. I look like a bag of disconnected limbs--arms and legs flailing in different directions, none of which is following her lead. There are times, I think, when I should …