G. Michael Hopf said (or rather, wrote) this quote in his 2015 post-apocalyptic novel Those Who Remain (Book 7 in The New World series). The full, original version he included is:
 
“Hard times create strong men. Strong men create good times. Good times create weak men. And, weak men create hard times.”
 
This quote is often paraphrased and constantly  floats around the internet in various forms, but it’s the same quote. Hopf has publicly confirmed he wrote it while researching generational theory (Strauss-Howe).
 
The idea of civilizations rising and falling through cycles of hardship and complacency is much older (echoed by thinkers like Ibn Khaldun in the 14th century and even Plato), but this specific wording and the tight four-step cycle is Hopf’s. It has since become a popular meme and is frequently shared without attribution or misattributed to historical figures.