"The aspects of things that are most important to use are hidden from us because of their simplicity and familiarity. We fail to be struck by that which, once seen, is most striking and powerful." --Ludwig Wittgenstein
There's a lot in this quote for actors. When looking at a scene, we have powerful urge to say to ourselves that we have dealt with this or that aspect of a scene, even before we have identified it to ourselves. We want to get it off our desks, as it were. I often think succeeding as an actor amounts to the ability to resist this urge.
Suppose you are playing a scene in which you are welcoming a sister who has been away back home. You talk about what has changed on both ends, eventually some grievances are aired, etc. But the most basic fact here is that you are SISTERS. This means a set of expectations, and a whole history of those expectations being met or not, confidences, rivalries, etc. All of this is bound to be of paramount importance in any scene between two sisters, and yet the question "what is it to have sister? " is precisely the kind of question that does not get asked BECAUSE it seems to be such a familiar relationship as to render the question unnecessary. But it is precisely these seemingly unnecessary questions that yield up the greatest fruit for actors.
Your character is a doctor. Why? Because of the money? It's prestigious? What's prestigious about it? Why does it have the prestige that it does? Why a doctor and not a venture capitalist, or some other highly lucrative or prestigious profession? These are the questions that must be pursued, relentlessly. But before they can be pursued, they have to be identified. To identify them, we have to learn to STOP ourselves in the act of shunting them aside, of getting them off of our desk, just as in the Alexander technique, you stop yourself from constricting your neck before speaking or moving. We have to own them. And then, when we appear in our scene, we will own something, and therefore have something to give.