People who can’t stand to see people suffering shouldn’t do medicine. This sounds counter-intuitive, but you’ll come to understand that everyone suffers and sometimes you can’t do anything about it.
People with sob stories shouldn’t do medicine. Your sob story ceases to matter once you get to the hospital. No one ever feels sorry for doctors.
People who are easily offended shouldn’t do medicine. Everything is offensive here: the patients, your colleagues, the smell of surgical wards. . .
People who are narrow-minded shouldn’t do medicine. The ability to think outside the box is indispensable to practicing in a third-world, limited-resource setting. The ability to treat all patients equally and without discrimination is also a useful asset.
People who are in it for the money shouldn’t do medicine. Seriously? Go do business. Who wants to spend 10+ years studying and then another 10+ years building your private practice so you can finally afford the house of your dreams? No one.
People with an aversion to normal social interactions should do medicine. From the awkward to the downright bizarre, medicine is chock-full of strange people discussing stranger things.