I have 3 dogs and a cat. Dogs require a minimum* of a one hour brisk walk per day, plus lots of mental games to keep them happy, healthy, and non-destructive. Doesn't matter how much you're working, or if you're sick. Beyond that, unless you have a busy, interesting household with lots of people around to interact with the dog, it will all fall on you. A dog isn't going to sleep all day until he gets old.
Cats on the other hand....easy keepers, and don't care if there's not much going on because it gives them time to look out the window in peace.
