My takeaway is that people who aren't self aware are less likely to be able to change for the better. Which I can agree with. How does one become self aware though?
I agree with the "humiliating experience" comments below, but how to curate that? One way is put yourself in a challenging environment you (and others) have to confront coming up short consistently.
EG: enter an academic program that isn't up your alley (eg, introverted dev? do an MBA.. You'll learn a lot besides the academics.) Afraid of confrontation? Try to become a manager and watch how you are forced to evolve your backbone. Also, try to get a job at FAANGs or other competitive places. Even failing interviews will teach you - where and why am I failing? Is it tech, communication, composure, etc? Even, try to date beautiful, kind people. Are they going for you - if not, what is it about you that's problematic? etc.
It's a tough way to live in the moment, but it's awesome in retrospect. You evolve and achieve what you would not have - but at any given time you may be more focused on what's holding you back from the next level..