First about 30 year old penises, my bf penis is right there, 30 years old. And it works quite well thank you ^.~ (oh, and I'm 27, and I work well enough)
As far as changing someone, I must say through the years I've changed a lot. But such things are very difficult to do, even when one is willing to change it doesn't guarantee success. Maybe you could be a mentor to her, see if she has any talents and encourage her to develop them. Young people are flexable and can learn quickly, but she could change in a way you dislike, or perhaps she won't change at all. If she had a talent, potential, an interest you should already be seeing a passion in her and you are not. If you keep it up you will have a hard road a head that may lead to lack of any fulfillment.