My friend's main study that he cites is https://www.sciencedirect.com/science/article/pii/S2095254621001010#sec0020 https://www.sciencedirect.com/science/articl

My friend's main study that he cites is https://www.sciencedirect.com/science/article/pii/S2095254621001010#sec0020 https://www.sciencedirect.com/science/article/pii/S209525462... . The interesting thing is that there is no real cutoff. The benefit kind of tapers off logarithmically, but all-cause mortality just gets lower and lower the more steps/day you take. So his 12k is somewhat arbitrary.