How come 40 can't be the new 40 instead of the new 30?

[Lik3]

It has been said that 40 is the new 30. How come 40 just be, I don't know the new 40? I just wonder what has happened to folks aging gracefully? I just wondered that for a while now and it seems like being old in this culture is not a good thing. It seems unfair that a woman between the ages of 30-40 would be too old to be a leading lady for instance, but that is only Hollywood. I am not old but what is wrong with it. I am still 40 but I think that getting older is great, but what will I know?