How do you teach a dog to play fetch?

I have two Cavalier King Charles Spaniels that love squeaky toys and chasing squirrels, and then I throw a ball and they sniff it and walk away! Can you teach a dog to play fetch?

Toss ball a short distance and walk to it with the dog. Say fetch and wait a moment; then drop ball again at dogs feet and say fetch again. Pick up ball and shove gently toward dogs mouth. Say fetch. He will eventually either pick up the ball or grab it. Give him his favorite treat and say, "Good boy". They're a bright breed. They'll soon get the message.

Well, my Cocker Spaniel LOVES chasing tennis balls. But then he'll take it and run away. So I'm assuming its a trust issue.Well 2 things you can do.1. Before actually starting the retrieve exercise, call him a few times and pet him and say good boy. Get him to realize that when you're calling him, you mean no harm. Then once he responds every time you call him, you can start throwing a ball. When he gets the ball, call him again. And pet him. He might drop the ball he might not. If he doesn't chase the ball, don't pet him. Just walk and pick up the ball and start over.2. Take 2 tennis balls, throw one. When he chases it and turns around to take it somewhere or whatever, just take the second ball and start playing around with it, bounce it around, tempt him, and then he'll come to get this ball and he'll probably drop the ball in his mouth, when he does just throw the one in your hand. Repeat till he gets it.Try a method for a week or so before going to the next, in case it doesn't work.Give them some time to process what you're expecting out of this exercise.

http://www.youtube.com/watch?v=7Nm4goEuBt4