>Eventually I realized that I was never grokking things with mathematics beyond a certain point. I was in office hours with the professor, asking how I could generalize the concept to a new problem. He said "just use your critical thinking skills! That's what employers are looking for."

That's the introvert's version of "just be yourself, you're overcomplicating it" -- i.e. just draw on innate skills that I have without realizing and you don't.