Teaching exposes what you don't actually understand
I started teaching programming alongside my engineering work expecting it to be a one-way transfer — I know things, I explain them. What actually happens is that explaining a concept out loud to someone who will immediately ask 'but why' exposes every place where your own understanding was pattern-matching instead of reasoning. Explaining why we reach for a specific data structure, or why a particular error-handling pattern exists, forces you to reconstruct the reasoning from scratch instead of reciting the conclusion.
The most useful thing I teach
Beginners default to solving the symptom in front of them. The habit I try hardest to instill is stepping back one level before writing code: what's the actual shape of this problem, and what's the smallest correct version of it? Debugging coaching follows the same pattern — resisting the urge to hand someone the fix, and instead asking the next question that narrows the search space, because the skill that transfers isn't the fix, it's the narrowing.
It's not charity, it's practice
Structured curriculum design, live workshops, code reviews, one-to-one mentorship — I treat teaching as deliberate practice on the same muscles I use in production work: communicating a design decision clearly, reviewing someone else's code without ego, and holding a mental model of a system precise enough to explain, not just precise enough to use.