I'm not sure that's good advice. 80,000 hours has given pretty good arguments against just "doing what you're passionate about".
Passion grows from appropriately challenging work. The most consistent predictor of job satisfaction is mentally challenging work (2). Equating passion with job satisfaction, this means that we can become passionate about many jobs, providing they involve sufficient mental challenge. The requirements for mentally challenging work, like autonomy, feedback and variety in the work, are similar to those required to develop flow. This suggests that a similar conclusion will hold if we believe that being passionate is closely connected with the ability to enter states of flow. If, however, you don’t think flow and job satisfaction are the same thing as passion, then you can still agree that…
There are better targets to aim for. We’re not only bad at predicting what will make us happy, but more easily detectable predictors of job satisfaction exist (autonomy, feedback, variety, making a difference etc). This suggests it would be more useful to aim at these predictors rather than directly at what we think we’re passionate about. Similarly, it could be more useful to focus on being good at what you do. First, this is a more positive mindset, focused on contributing rather than taking. Second, being good at what you do makes you better placed to ask for engaging work.
Related: http://80000hours.org/blog/63-do-what-you-re-passionate-about-part-2
A friend of mine who may want to Earn to Give for the purposes of effective altruism mused 'The wages of American doctors seem inflated right now. I wonder if it is likely that the American health care system will be fixed by the time I am able to work there. If I do go to med school that is.'
Right now, he is an undergraduate student from, and living in, Canada. He is about half-way through a degree in computer science, but he is taking some biology electives. There is a good chance he will switch his major completely to biology, because he no longer believes he wants to become a programmer, and because he is very passionate biology and the study of life, and he would rather go into grad school for biology, or maybe medical school. If he already completed several credits from a previous major, and by December will have done 2 semesters worth of biology classes, I expect it will take him at least another 3 semesters to complete his degree, and/or complete the prerequisites for medical school. If he gets into medical school 2 years from now, it will take him another 4 years of medical-school+residency to be able to practice in the United States, and 2-3 years more than that if he specializes, or goes to a medical school in the Caribbean (where getting into them is apparently easier than mainland medical schools, but to complete the training takes six years). So, it would be at least 6-8 years from now before he is a practicing doctor in the United States.
So, does anyone have any ideas of how to go about the solving the initial problem? What is the likelihood that the wages of American doctors will deflate in the next 6-8 years due to major shifts in how the American medical system is run? What sorts of changes ought one be looking for to answer this question: political, bureaucratic, technological, or cultural change?
edit: my friend in question has expressed interest in this thread, so if you want to make recommendations about or discuss medical schools in the United States vs. other places, or in general, or about entering the medical profession vs.s other jobs, go ahead. Such valuable information would be appreciated. I don't yet know if he himself will participate in this discussion.