Psychology is a field that aspires to some day exist as a reliable body of knowledge. It's a nice idea.
As Peter Drucker indicates, happiness, like money, comes when the system is working. You don’t aim for the money and you don’t aim for happiness, you aim to make the system work.
Your mind is a collective but you don’t see it as a collective. You can’t see the parts because the parts are doing the seeing. We are fascinated to look at ourselves because it helps us imagine what we are.