"Into" implies "(going) into" there is some type of action involved going from the outside to the inside. "Within" is synonymous to "from inside". You are already inside.

I am gathering that "into,” within the context of the sentence, means she is stepping into the building. She is only capable of working within the confines of her job and cannot stray into various other modalities. Or more simple: What you have within you makes you who you are. The situations you put yourself into become a part of your existence.