Previously I cautioned people not to overestimate their knowledge, and to keep an open mind.

There's an opposite problem - many people say, "I couldn't work this out. This is beyond me." To that I say: "Don't underestimate your potential."

Again, an aside, outside of health. Another of my interests is languages, and some years ago I got a diploma in Spanish. (Three such diplomas in different languages makes a degree, so my Spanish is at degree level.) I'd say my Spanish is good, but that's all.

I used to know an English guy whose Spanish was perfect. He'd visited, but never lived in a Spanish speaking country. I heard Spaniards tell him, with amazement, that he had no accent at all. That level of skill in a foreign language is very rarely reached. His work was as a cleaner - so he had no advantages there. To my knowledge, he had no formal qualifications in Spanish.