If you've got a self-propelled lawnmower, a stake, and some rope then there's no reason to waste your day sweating in the yard. Just use a setup like this and your lawnmower will do all the work on autopilot.

Then again, you could very well damage something with a runaway lawnmower if things go wrong, so perhaps this isn't the best of ideas. [YouTubeThanks, Jess!]