Yeah, but his point is that you really have no idea. I mean, you have interests, but at this point you really cannot even match that to specialties. It takes a lot more exposure to something to see what it's really like to be doing that. And you can't dismiss the realities of medicine. You may end up loving pathology, but do you love the fact that their job market is horrible and many residents have trouble finding jobs? Maybe you like kids, but if you have $300,000 in debt at the end of residency, do you really want to try and make it off $150,000 salary?
It's good to have interests and aspirations, just know they really are just shots in the dark at this point until you get more exposure. Then there is the reality that you don't always get what you want. You might want to go into radonc or derm or optho, but many simply won't be able to get in. There's plenty of time, just keep your mind open to the possibilities.