Best way to explain the magic system when the main character is already experienced with it?

In most books the main character is learning how the magic works right along side the audience. This makes a really easy and convenient way to explain the magic to the reader, without having to info dump on them. In my book I'm writing the main character has already been using the magic in this world for her entire life, so I don't have that convenient option to explain it. How would you go about explaining that through the writing in a way that feels natural? Also any examples of books where this is done?