I wonder how they know it is modifiable? Without splitting the population into “folks we told to exercise” and those who we did not, you can’t really know how s

I wonder how they know it is modifiable? Without splitting the population into “folks we told to exercise” and those who we did not, you can’t really know how successful such a program is. People that feel good and aren’t sick will be likely to exercise more, so there are confounding factors.