That may be reasonable -- though the amount of physical activity in construction jobs also seems to vary a lot; many operators of heavy equipment such as bulldo

That may be reasonable -- though the amount of physical activity in construction jobs also seems to vary a lot; many operators of heavy equipment such as bulldozers or cranes are actually fairly obese. Not to mention the culture of smoking (at least where I live; the difference to general population is noticeable). I do office work but commute by bike; I'm also not enthusiastic about jogging on top of that.