Here's Peter Attia graphing this, https://youtu.be/vDFxdkck354?t=929It's just the opposite of jumping off of a tall building; while traveling down, everything is fine, it's the quick stop at the end that's the bad part. But traveling down hill health-wise is not at all fine. The eventual stop at the end is probably going to be a relief.
We all will traverse from healthy to dead. The idea of "healthspan" was something I liked more than "lifespan". The graph would be relatively flat in the above 90% healthy range, maybe gentle slope down for a while, then a cliff. That, as opposed to a steady downward slope, 70%, 60%, 50%, 40%. I don't know what it would be like to be 40% healthy, but I'd guess it's no fun.
It's been said many times on this board and elsewhere, that you're perfectly healthy until suddenly you're not. At that point, you start thinking more about the shape of the graph and at what angle you'll be hitting the X axis, and what that ride down is going to feel like.
Less than 10 minutes to get the point.
To see the whole video, drag the curser back to zero.