I have three dogs of my own (one in each size: S, M, L) which in effect turns my backyard into a part time dog park. I work off-site for about 6 hours a day three to four days a week, at which times your dog would be crated (if necessary). I also visit my parents on Sunday afternoons, but aside from that I spend most of my time at home either working, studying, or cleaning up around the house. If it's not too hot outside, I try to take all the dogs out for a mandatory playtime outside for 30-60 minutes so they can burn off some energy and bond with the other dogs once to twice a day. Other than that, they are free to come and go through the doggie door as they please with the exception being if it's raining outside. At least twice a week I like to do training sessions with all the dogs where we just practice their basic commands (sit, stay, lay down, shake, etc.) Some dogs really enjoy it, but some older dogs aren't as into it, so I will have them do a treat puzzle or give them a dentastick instead, so they're at least getting something out of the time the other dogs spend practicing commands with me. Full disclosure: I am NOT a certified dog trainer by any stretch of the imagination, but I do enjoy working with dogs to teach or refresh them on basic commands.