Have your dog sit and then stand repeatedly. This exercise is equivalent to human squats. (When you have your dog stand, you want his front feet to stay in place. You do not want him to move forward when he is standing because that does not work the appropriate muscle group) 

Have your dog lie down and sit repeatedly. This exercise is equivalent to doing push-ups.

Have your dog in a down position and get her to move forward while still maintaining the down position.

Have your dog walk up and down the stairs several times.

Either buy a Kong or another form of treat dispenser and place the dog's dinner in the dispenser. This way the dog is earning his dinner.

Put your dog in a "sit-stay," and go hide somewhere in your house.  Then call your dog to come find you.

Have your dog standing in front of you. Then step in toward him and have him step backwards. Increase the distance of your dog walking backwards until he can take about seven human steps backwards. This exercise works the rear leg muscles.

Have your dog stand and place a cookie by her chest. Once she lowers her head, start to lower the treat and push back slightly so that she will keep her rear end up. This exercise stretches the dog's forelimbs and helps with strength in the rear. Also, doing this exercise multiple times in a row is similar to the doggy push-ups mentioned earlier.

Have your dog make a circle to the left and then to the right or vice-versa. This works the flexibility of the dog's back.