
I have avery large 6month GSD x Rottie. She gets a quick barely 5 mins walk round our small block in the morning and then approx 30 mins later in the day.
She does run around and play with my 11month JR in the house but I don't allow them into the garden together as they go wild. She does however like to retrieve a ball I throw in the garden ( I only have a very small garden so not far to go to get it.You could give yours a 5 min walk in the morning and a 15 min one in the afternoon.
I find this quick 5 mins in the morning settles them quite well as they feel they have been out and the longer one later mentally satifies them more.
You can also do training at home to stimulate and hide some of his food around the house instead of feeding it in a bowl so he has to search it out. All this helps to keep them mentally happy.
Bev