Are there any activites for a dog with a broken foot?

My boyfriend's black lab has a broken foot, and he's really bored. He's been splinted and the vet has said NO unnecessary activity. I've gotten him a nylabone and some stuffies to tear apart, but I'm wondering if anyone has any ideas to keep the poor guy entertained without letting him run around. He's a VERY active dog, and it's heartbreaking to see him sitting with his leg in a cast, staring at his soccerball and whining.