I taught my Aussie, Mojo, to play with toys by using a clicker. He thought toys were beneath him until then. lol
You're going to think I'm crazy with what I did for my dogs that already enjoyed playing. lol I would pick a special "toy". That toy would be kept up out of reach and at first I would only pick it up randomly and act really excited about it. I do this on and off during the day, making sure the dog was paying attention, for about a week.
After the dog realised this was an exciting thing, I would start including the dog after picking it up and getting excited about the toy. I would always put the toy back afterwards, since it was a SPECIAL toy, not one of those meager everyday toys.
![Wink ;)](https://bigpawsonly.com/Smileys/default/wink.gif)
After lots of interaction like this, I would start using playtime with the toy as a reward for the dogs 'work'. The more hyped up you get about the toy, the more excited the dog will be.
![Smiley :)](https://bigpawsonly.com/Smileys/default/smiley.gif)
It also helps if you have an idea of what kind of toy the dog prefers. Mojo loved tuggies, but Faust(GSD) and Zeo(BC/Sheltie) loved balls & frisbees. So learn what his preference is and then build on that. Being a GSD, I'm sure that he won't need too much encouragement to "turn on" to a certain toy anyways. lol Good luck with him!
![Smiley :)](https://bigpawsonly.com/Smileys/default/smiley.gif)