Ask HN: How did you taught yourself First principles thinking?

I was watching one of Blitzscaling episode[1], where Reed Hastings talks about building Netflix. To quote one of the question:

Q: Do you have a culture check in the hiring process?

A: It’s not a checklist. It’s easy for people to say, “I love the culture deck.” You ask, what did you disagree with and why, and if they don’t know anything, they’re not a first principle thinker. We’re looking for people who are curious and question everything around them.

My question is how do you learn or force yourself to become first principle thinker

[1] https://www.youtube.com/watch?v=jYhP08uuffs