We have a Heeler that we got from the Australian Cattle Dog Rescue Association (ACDRA.org) based out of NY state, he was approx 2 years old when we got him. The association had quite a interview process for placing their dogs but if you are good person you'll have no problem.
The Heeler or (ACD) is an amazing canine! Absolutely Amazing! So smart, too smart, he runs our family. Plus the athleticism is mind blowing, my cattle dog is a little guy only 40lbs and he can easily jump over me while still catching the frisbee, he does really well BC skiing, and in general is an amazing animal. He is a little mouthy though. He likes to make sure that people understand he is second in charge after me. Heelers are very loyal, and exceptionally obdient to there owners, but are not scared to boss other dogs, people, animals around. My cattle dog will take as much or as little excercise as I give him. Sometimes he's happy laying on the couch as much as he is climbing a mountain.
He has been very supportive of me while I am recovering from a torn ACL.