Do we really need gyms?

I have looked at this site

http://www.weightlossresources.co.uk/exercise/tips/housework_workouts.htm

Did you know that you can burn 193 calories an hour by hoovering and mopping floors, burn 173 calores an hour dusting and 113 calories an hour by doing the ironing? Moderate walking up and down stairs burns a whopping 516 calories an hour!!!

Walking is considered the best form of all round exercise but you can top that up with housework and you gain all round by getting fitter and having a nice clean tidy home.