Just like the people who take the stairs rather than the elevator in order to get a little exercise, mow your lawn with a lawnmower that lacks self-propulsion.
If you’re going to spend an hour or two walking in monotonous, geometric patterns on your lawn, you might as well be getting some exercise in the process.
Pushing a 100 pound lawnmower (the average weight of a push mower) is a great way to do it.
I spend the 60-90 minutes that it takes to mow my lawn listening to books and podcasts, rehearsing stories for the stage, and pushing like hell.
I hate doing it, but it’s an exceptionally productive way to spend an hour.