Dogs get out of shape too

I tried to run with Nero my dog today. He is a Schnauzer, so not a very big dog. He used to be able to run four miles, easy! I thought he would be able to run them without a problem because he is a dog, and I don't know why I assumed that dogs have higher stamina than humans. Anyway, it turns out that my lack of running afected him as well, and now we are both out of shape. He stopped for the first time at one mile. We took a two minute break, drank a little water, and started again. I feel like the first break encouraged him to stop more often though, because he started stopping every few hundred meters after that. I felt bad, so I decided to only run two miles with him and even at that, I had to carry him the last fourth of a mile. Poor thing was out of breath. I was kind of excited I could out run my dog, to be honest. Bottom line is, our furry friends get out of shape too.