Going for a walk is something I tend to enjoy too, and I really recommend the app runkeeper + a fun music album or an audio book.
Runkeeper is really good at motivating me at least, and it's fun to set your own goals.
It probably would, knowing myself (it helped when I had a guinea pig, and those aren't even as cheerful as dogs).
And if it didn't, I'd be emotionally attached to it anyway.
Dogs are life. Be damned SURE before you go down that road, though; they are sentient, loyal, and deeply feeling creatures, not 'toys' nor possessions to be discarded and grown bored with.