On the other side of that, what I've noticed is that if learning is not fun or at least seen as relevant to something someone wants to do, it gets forgotten no matter how important it was (the number of native English speakers I know who can't write grammatically correctly or spell when they actually need to is not insignificant, and neither is the number of people who think I use "big words" like insignificant, and they went to school).

And uncomfortable things can still be fun (as much as I can gather from the people that keep doing nonsense like gymnastics XD).