That's right. I used my Garmin Forerunner 305 to track my lawn mowing one day, to get an idea of how much of a workout it is. It turns out that on average it's not too bad if I mow aggressively, and consider that the back yard requires about the same effort as the front (I tracked only the front yard). I doubt I'll track my my heart rate and and path every time I mow my lawn in the near future, but I will be mowing the lawn more, and it is certainly a workout. At the very least, it's equivalent to short recovery run or something.
I often think about this. The reason I was resistant to running before I started running again last year was that running for the sake of running didn't appeal to me at the time. Why just go out and run when you are not running to some particular place for some practical reason? What sense does it all make? I guess that's why I try to turn some of my errands into runs. A trip to the post office to mail the taxes or buy stamps can easily be incorporated into a 3-4 mile run, as can a trip to the bank for a deposit, or to the video store to return a movie.
Healthy AND practical. That's what I'm talkin' about.