How to "know" if I have a passion? Most students encounter a life-changing decision during their undergraduate years. That is either to choose a high-paying career, yet such that they might not be passionate about or a career they like but is unlikely to be high-paying.

It is not unusual to find career advice popping in various internet circles that fixate on the importance of passion. The general rhetoric is "If you have a "sufficient" passion for X, you are guaranteed a "good" career in X and hence a good life." 
Now, on some levels, the advice makes sense. Students are usually willing to sacrifice guaranteed-to-pay-well professions in hopes to excel in their own professions fueled by passion.
Now my question is, What is the sufficiency precisely in this context?

To be more precise, say I think I feel passionate for mathematics. Maybe because I am good at it. Maybe because I contemplate on it in my free time. Now when it comes to the actual profession, the "apparent" passion fades away and I am left regretting pursuing the field (something that is not unusual to see with Ph.D. students).
Or say, I feel I like physics and mathematics but I also get easily swayed away by high paying professions like data science. 

How can I come to "know" whether I truly have a passion for mathematics or whether I was merely deluded into thinking that because I was made to feel that I am good at mathematics by the relevant education system?
If you were really passionate about something, you'd know because you'd want to do it in exclusion of all else. You think about that thing even if you're bathing, eating, etc. 

Having said that I can understand what you're asking because if we define passion this way, precious few people would be passionate about anything that they can actually make a living from. That includes academics - e.g. this question


  I just want to get married, and have weekends and evenings off, and chill out and play board games, and have nice conversations with friends, and have time to exercise and eat good food, and partake in hobbies, and read books and play computer games and watch movies and write a novel or two.


And from there it's just a short way to "I just want to get married and have my entire week off ..."

So now what? I suggest:


Can you imagine yourself doing it as a career? You don't have to like it more than board games, conversations with friends, etc, but you should like it enough that you can do it for upwards of 40+ hours a week. On the other hand if it starts getting painful to go to work every day, it's not a good idea to do it.
Are you good at it? If you are, then you can get results even if you aren't passionate (by above definition) about it.


It may not be a popular position, but you can certainly base your career around things that you aren't passionate about (by above definition). For example, my mother became a doctor because that's traditionally what all good students at her high school did. She didn't particularly like it any more than other careers, but she studied it, did well at it, became a trained doctor, became a specialist, and eventually managed her own department. She would often complain about her work at the dinner table, and talk about e.g. how she would rather teach language at a local high school, but by all metrics she still had a successful career.