I think this question is funny, yet legitimate. The notion of “calling” can be hokey, like those evangelical tv stations showing every person with a motor deficit being “healed” in front of the congregation. I haven’t met, heard of, or read about anyone who went into medicine as a result of some direct communication with any deity. So medicine is not that kind of calling.
Medicine is a calling, in the vocational sense. The proof of this is how many doctors dislike their jobs. A consistent 50% of physicians polled would not recommend a career in medicine – get one of these people talking and they will admit that they chose medicine for the wrong reasons, and that they did not know what medicine is actually like. Many say, “I wish someone had told me how hard it is.” You must be right for medicine, and medicine must be right for you.
If you are not right for medicine, it will crush you with its bureaucracy, long hours, and high liability. Then, just for fun you will get splattered with some stool, vomit, and choice purulent bodily fluids. You will be colonized by MRSA and C. Diff, and you will not think this is funny.
On the other hand, you may have the raw materials of a fine doctor, but medicine may not be a good fit for you. If you don’t actually like medicine, how could you be happy practicing it? As I’ve said, there are already enough doctors who do not enjoy their jobs.
So, you ask, “Is medicine my calling? How do I know if I should be a doctor?” You need to start by getting to know what medicine is actually like (on a side note, do not even consider applying to medical school until you know what medicine is like…med schools will sniff you out immediately). You need to spend a lot of time around sick people and see how it makes you feel. You need to spend enough time observing doctors to understand how repetitive their job is, and ask yourself if that would wear you down. Once you know what medicine is all about, be honest with yourself about whether or not you love it. Ask yourself two questions. “Is medicine a good fit for me? Am I a good fit for medicine?”