How do I cope with how much I have to know in medicine?

The sheer breadth of medicine is real. Every system of the body, every way it can go wrong, and you are expected to hold it all. Feeling overwhelmed by that is not a sign you are unfit. It is a sane response to an enormous field. No single person holds all of it. Not one. The doctors who seem to know everything do not. They know how to think, where to look, and when to ask. That is the skill that actually matters, and it is learnable in a way that memorizing everything is not. You build depth over years, one case at a time, and you keep references and colleagues close for the rest. Trying to know it all at once is the thing crushing you, not the field itself. Let go of the whole and focus on getting a little better at what is in front of you this week. Depth comes from repetition, not from panic. Trust that the breadth fills in slowly, because for everyone before you, it did.