Our yard is not fenced but he had a dog run. When he wanted to go out I would tie him there, when he needed to go out (one of his scheduled potty times) we would walk around the house twice to make sure he did everything he needed and then go in. Then he had one good walk a day. He was not an active dog especially when he was older but would be more than happy to get active when you said "walk" even though after the walk he would have to lay down on the cold floor for about 15 minutes panting very hard to the point I got worried. That's mostly because of the amount of effort it takes to pull with all his might on the walk *sigh*. But yeah, if it was warm her could spend an hour at a time sun bathing. If it's cold he would not want to be ties out for more than five minutes and if there was snow we even had issues getting him out long enough to poop (I had to dig out a path for him because the snow made his feet cold).
