Jillian Michaels Challenge

Just did it this morning .... either I must be getting better or it must be getting easier...no more sore legs.... What I don't understand is how come my arms aren't sore from using the 5lb weights??? I am a non exerciser so I expected them to be a little sore at least but nothing... anyhow.... I am planning on incorporating her new video banish fat boost metabolism too ....any supporters for that one... ???