Winter is a tough time for dogs like mine who can't really go out for long periods of time when it's cold.   If you need a new game to teach your dog, try "Find it!" Find it is a game that most dogs love! Start by asking your dog to sit and stay (If he doesn’t know this, you can have a friend gently hold him in one place).  Have a treat that your dog loves, show him you have it and place it about two feet away from him (out of nose reach!) . Then say “Okay, Find it!” (Make sure your helper knows to release your dog) Be sure to praise your dog when he finds the treat and, of course, let him eat the treat. After a few repetitions, you should be able to increase the distance and even start hiding treats in unusual places. Be sure to make it challenging but not so much so that he gets frustrated and gives up.  And remember to Have fun!  Don't forget to read my post on how Karate Training is like Dog Training.