After the First One

People tend to talk a lot about the first person to do something. First person to walk on the moon, for example. Rights movements also have their firsts, the people who first break through an absolute barrier. First woman doctor, first black politician in US, etc.
My question is, after the first one, what do we do next? How do we get from that point to the one where it's nothing strange, where we have plenty of women doctors, or black politicians, or whatever. Even now, when women doctors are nothing particularly odd, there's still inequality, with the glass ceiling and less women than men choosing to be doctors in the first place.
Tamora Pierce is a fiction writer. She has written several books set in a land called Tortall. The first series was Songs of the Lioness. The star of that story, Alanna, disguises as a boy to become a knight. After she gains her shield, her gender is revealed, and the king declares that girls are now permitted to become knights.
Then she has a series called Protector of the Small, about a girl named Keladry, the second girl in Tortall to become a knight. Alanna pushed open the door for lady knights, but it's not completely open. She is an oddity and treated badly by many of the other knights-in-training and the ones who teach them. I really like this series because it shows that it is better, but still not perfect, compared to when Alanna became a knight.
The absolute barrier of 'no X allowed' is easy to see. It's easy to know what to fight. But what about the barrier where things are just simply harder for X people, not due to inherent lack of ability but the effects of discrimination. How do we fight the problem of girls learning that science isn't a 'girl thing' and therefore not seeking careers in science? How do we fight the problem of organizations hiring 'tokens' of various groups so they can point to them and say 'see? we're inclusive!' without really changing anything? I don't really know the answer.