Is mowing your yard considered exercise?

I see people mowing their yards with various lawn mowers all summer and I wonder if that can be counted as exercise.  My thoughts are riding lawn mowers don’t offer any exercise benefits because you are sitting during the mowing session.

Walk behind, self-propelled mowers offer you some exercise since you are at least walking during the session. I cut a fairly big yard with one of these and I do get my walking in when I use it.  In my opinion, walk behind push mowers offer better exercise because you are walking and also pushing with your arms and chest to keep the mower moving.  My yard could be cut with a rider mower, but instead I have a self-propelled and a push mower.  I alternate between the two throughout the spring, summer and fall.

Let me know your thoughts on mowing the yard in terms of exercise.