A very good friend of mine has a Greater Pyreneese as does his family and a couple of neighbors. The Pyreneese are great dogs, but by nature are just not playful. We always joke around about how much they lounge around and don't seem to really burst out much energy (especially compared to my GSD). I wouldn't worry too much. You just got yourself a breed with a notoriously low-activity level. There is probably nothing wrong with him. It's just a trait of the breed. For those of us who have dogs that want to play 95% of the day, having a dog with a lower activity level doesn't always sound too bad .