This one is going to take quite a while to do. You can choose to Walk or Run to get this, so I would suggest running to every location you need to go to on your crop/animal runs. For an example, I ran the full perimeter of our farm and filled about 1/30th of the Achievement Tracker Bar.
Another thing to note, the Achievement Tracker does NOT work while on the farm, but it IS still counting your progress. Once you exit to the main menu, it will update your progress.
TD BradleyHeat makes a good point. You can buy pavement types with Diamonds and place those on your farm. When running on pavements, you will run much faster and will cover more ground than running through your crops or grass.