You're quite right of course (although actually, it seems very plausible to me that fit people are more likely to stand more / choose jobs where they will stand

You're quite right of course (although actually, it seems very plausible to me that fit people are more likely to stand more / choose jobs where they will stand more) My comment was mainly out of the frustration I have because so many interventions are very difficult to do and so I want good confidence that they will actually make a difference, but most research just gives you at best strong correlations. Still, I've got a standing desk now...