Because of the imprecise way the op phrased his question, I think you've misinterpreted it. I agree with sibling comment (jstx1) that op is not asking about "good" as a skill-level change from beginner to expert.

Instead, the op is asking something like... "How do I find the one activity that really activates the dopamine reward feedback loop in my brain which in turn makes it effortless to stay focused on it because I'm magically in that flow state?"

And because most people who ask the above question are not clinical psychologists using precise scientific language... they end up expressing it in the lower-resolution form of, "How do find the thing I'm good at?"

But then language lawyers laser focus on the word "good" and think op is asking about skill... which leads to "well you can't get good at a skill unless you practice that skill" ... which isn't really what the op was asking.

>Instead, you do what you are interested in,

Yes, and that's the step the op is having difficulty with. Lots of people are trying to find that thing that really interests them to trigger more success in their professional careers.