The 8 hour day contributes, sure, but it's more than just that. Because I live in a city that allows it, I walk to/from work and to/from lunch every day. And to

The 8 hour day contributes, sure, but it's more than just that. Because I live in a city that allows it, I walk to/from work and to/from lunch every day. And to/from any other errand that needs doing. People who drive to suburban office parks do none of this. It's not just what you're doing for the 8 hours that you're at your desk. A lot of us have arranged our entire lives to require no physical movement.