I came across a very interesting article on Aeon about the how stoicism can make people more powerful: long story short, the author argued that those who find themselves in difficult situations are lucky.
A quote from Roman stoic philosopher Seneca about what he would say to one whose spirit has never been tempered or tested by hardship encapsulates the rationale behind this argument perfectly:
You are unfortunate in my judgment, for you have never been unfortunate. You have passed through life with no antagonist to face you; no one will know what you were capable of, not even you yourself.
Indeed if we don’t know what we are capable of, we can’t make improvements in areas where we need to work on. This is basically the more elegant version of “what doesn’t kill you, makes you stronger.”
