But...if 50 is the new 30, then that makes 40 the new 20. According to the theory of making shit up and applying math to it.
See, I think it's actually very accurate, no matter how much women may not want to be 20 again there are a lot of parallels. 20 is the age we all really figure out we are out in the world on our own, and start to really come into who we are going to be as a independent person. Whereas 40 is the age women start to really come into who they are as a fully grown adults, sexually realized and having accomplished most of the things women are "supposed" to do in their life. And it is the start of figuring out where to go from there, and what your life will be now. At 20, we look ahead at what we will be for our young life, and at 40 we look ahead at what we will be for the rest of our life.
Take this with a grain of salt, because, of course, I'm a guy in my late 20's. : )