How do women just have this "knowing"?

I (23 F) have always been baffled by women who just seem to "know" things about life. They don't really think about big things. They just get a tattoo, they get engaged, they travel the world, they make friends without much thought. I don't know how to explain it, but they move in a way that just feels like they just know. Maybe it's just confidence.

My question is to the gals out there, how do you know what tattoo you want? (or any other example) Were you always confident or did you learn to be like that?