If only we could allow this one concept to be our guiding light, I guarantee we would see the sunny side of our girls more often. A young teen I know talked about how she was able to handle an emergency by knowing that she was in good shape. One day a man followed her in a car as she was walking home. Because she was in good shape she knew she could run if she had to get away. This single event demonstrated to her the depth of her own self-confidence.
Body image is a huge issue for girls as they mature because it determines their self worth.
Sports helps girls get used to and appreciate the body shape they've inherited. It makes them realize that their self image isn't all about weight. Eventually girls learn that building muscles means building a new and improved shape. They want to copy them, to experience the fun gained by being competent. If an activity looks appealing, your daughter will want to try it.