Yes, they are always thrilled to go and they never run behind or beside me. People make fun of me and say they could run too if they had two sley dogs to pull them. The tension on the leashes are always tight. I've seen them get over heated on maybe a couple of occasions and stopped running. I got started too late in the morning. In the summer, I run between 6am and 6:30am, to beat the heat. I think my biggest concern has been their bones and like someone mentioned earlier, the pads of the feet. I'm not going to take them all the way to a full marathon. I can have one long day without them (I'd miss them terribly) I'm going to just keep them at 1 and 1/2 hour three days a week and walk them for 1 and 1/2 hour the rest of the week. I really appreciate those who are concerned, because I go absolutely crazy when I see an exhausted dog trying to keep up with his or her owner (can't think of another more endearing term) when they are either running or riding a bike, which really makes me mad. Anyway, obviously I asked about exorcise, because I do love my two girls and can't imagine hurting them intentionally. They are the love of our lives. These are my husband and my only kids. We've been married 28 years and have always considered our pets family.