I thought I had made up my mind when I decided that a Sheltie would be my next dog, until I saw one about a month ago. They are rather short and I want a dog that is able to go on runs with me. I was wondering if a Sheltie could keep up. I'm sure they have the energy, but they seem so small. Then I was thinking that I might want a larger dog. I really like Aussies, but how much exercise do they need? (And what counts as exercise?) They sounded similar to Shelties in that they are smart, reserved around strangers, vocal, etc. I assume those are just traits of herding breeds in general. How do Aussies differ from Shelties?