1) drive stake into center of yard
2) attach one end of rope to said stake
3) attach the other end to mower with appropriate length
4) turn mower on, walk behind for one rotation to make sure it is not going to hit anything
5) get favorite beverage and comfy chair
6) sit down and enjoy your birthday while your lawn mows itself
7) clean up the edges where the radius length of the rope doesn't reach
8) profit