Most people wouldn’t argue that young individuals could excel in a field of their choosing if only the knew what they were passionate about. I would not give the advice ‘follow your passion’ to young individuals like most inspirational speakers. I would rather say to them foster a passion.
If you can’t find your passion, foster one. How do you come about this, is by trying things out? Go there, try this, do that. You don’t know what you dislike till you try it. Never assume, instead give things a go. Be it running, cooking, photography, portraiture, landscapes. Whatever it might be, you will only foster a passion through trial and error. Try something.
A good way to know if you’re passionate is to follow what interests you. After finding out a bit about it, longevity will tell you if you have fostered a passion for it. I love photography and always came back to it throughout my life. First as a child, then in my teens, to a young professional which I kept doing into my adulthood. With a passion, you love doing and learning more about it. You might have parts of the job that you dislike but you will find them necessary as a whole when it comes to your future goals or achievements, and your happy to have a little bad with all the good.
So to follow your passion you need to find it first. To find your passion follow your curiosity, and put your curiosity through the test of time. This is how you foster your passion. So go out there and try, find, follow and cultivate yourself. Because to become a genius, first one must master their craft.