We've had joggers go from a nice jog to a near full-out run when they pass our house and see Olive doing her thang in the yard (chasing leaves, sticks, whatever, on a leash held by her human no less!). She's not paying any attention to the joggers, but she can look pretty darn fierce and has quite the bark. The joggers who have met her think she's hysterical because she goes from fierce Destroyer of Leaves to sweet butt-wiggling sheltie in a split second.