Suggestion. (prob'ly a hard one) Swap jobs for a bit, and have her do the mowing a time or three. That might bring home that it is not only the destruction of tools, it is also all the stopping and starting, climbing onto and off the mower, etc. Assuming you are talking about a tractor or riding lawn mower, but it don't really matter. Havin' to stop a push mower to move stuff, then yanking that cord to start it up again is equally a pain-in-the-butt. There is nothing quite like the experience of running over a tool you yourself left on the ground, and hearing and seeing the tool, the mower, or both, mangled....