Fair point, Sam. I'm usually thorough about noting correlation vs. cause-and-effect, and I've added a note to clarify that regarding this study ("found a link between walking faster and good heart health, though it does not prove cause-and-effect"). But that caveat aside, there is a sea of evidence linking walking, and walking faster, to better health and longevity, so I tell people that whichever way the cause-effect goes, there's no doubt that moving more helps us move more, and that's good for the mind and body. Still, you get 5 points for spotting the shortcoming. I have no idea what the points are good for, but thank you!