I have a self-propelled gas mower but I never use that lever, I always push it to get the exercise. I had a push mower years ago that I mowed at my Mom's house with. I have an antique push mower in the garage that I picked up at the curb a few years ago--and I figured I'd make a nice yard art display, along with a rusty wheelbarrow that is missing a handle and a wheel, etc. But I have always wondered if the mower could work if it was sharpened. There isn't much that can go wrong with them that can't be fixed with some lubricating oil and a file.
The yard here is big, a half-acre, but I don't always mow both front and back in the same day, so it would be fine to break up the job for a mower like that.