Doctors make the worst patients.

proverb It is difficult to give people help or advice on something in which they are professionals, because they often feel as though they already know better than anyone else how to handle the situation or perform a given task. Mary tried to convince her boss at the bank to see a credit advisor about his growing debt, but he kept insisting that he knew how to manage his money. Doctors make the worst patients. A: "Of course Dad hasn't gotten that rash looked at yet. He says he knows, as a doctor, that it's no big deal." B: "Ugh, doctors make the worst patients." Good luck teaching your teacher something new. Truly, doctors make the worst patients.