How to explain antifragility to 90’s kids: there was this great “anime", Dragon Ball, very famous in Japan and Europe (almost everyone born in the early 90’s knows it). They still keep streaming it in Italy.
To sum up, there are these guys, called Saiyans, coming from another planet. What does make them stronger than other fighters all around the universe? Local antifragility. You can beat them to death, but if you don’t kill them, the closer they get to death, the stronger they will come back (once recovered). Even trying to bug them or hurt people/things they care about would be bad for you: the growth of emotions such as rage or pride would give them strength! Their favorite type of training is to go beyond their limits (like lifting weights with boosted gravity or pushing their bodies to the limit), and they’re always looking for battles and troubles. This is all shown in the series “Dragon Ball Z”.
Maybe it’s stupid but I find it a good analogy. I grew up with this anime and I thought about it as soon as I read the first three chapters of your book.