I break into a secret government base and steal a time machine, then I use the time machine to travel into future and undergo life-lengthening processes that allow me to live for 5,000 years or more. I then travel to the past, when the hill was just a single, unimportant grain of sand, and I sit down to wait a few thousand years for it to slowly accumulate into a hill through weathering and various geological processes, and when it's finally a hill, I successfully claim it as MINE before anyone else can.
My hill!