I have to find a spot where there are no sheep around, as farmers are able to shoot (wild) dogs running with intentions on the sheep. Anything that runs is fair game. Mine love the free running. Find a football/cricket ground, or even tennis courts, to let them have a free run. As Sally Zande says, let em run. If there are two of you, drop one person off, and drive further into the woods or whatever, then let them out. It is fascinating to see where they go. And see who is the first to come back or to the other person.
They will come back...you just have to wait.