A retriever? I can't tell you how glad I am to hear that! LOL

In my experience, I've found retrievers to be both the most intelligent, and the most idiotic dogs you will ever come across. You can use this to your advantage in all sorts of wonderful ways. They are idiots, so the strangest things will give them pause, but they are intelligent enough that they don't forget what they've been taught.

One strange success story was a Lab that chased cars. The family got the neighborhood kids together and had them all hide in the shrubs with garbage can lids and sticks. When the dog went for the car, all the kids hopped out and made quite a racket. Scared the dog near to death. To this very day (3 years later, mind you) when a car drives by, the dog will start to run, reach the bushes, stop for a look to make sure nothing is hiding, and by then the car is long gone.

I also agree with Sorcha. There really is no substitute for a fence or kennel when the 'people' are gone. You can get a simple 7x7 enclosure for about $150, enough room to stretch, food and water and toys, but with a retriever, you don't want to overdo it. They get bored really quickly, and you could be ending the car-chasing behavior but inadvertantly encouraging nasty things like boredom chewing/licking/barking.

(Enjoy those 5 mile runs, I'm proud of you!)