[Mojave's Mom]

I think Camille's description of what to do is excellent ;)

Don't wait for the dog to already be standing and at the end of the lead when you correct her. Whoever is holding the dog must be watching the dog and not the ball. As soon as the ball is thrown, correct the dog as soon as it makes that first small move to go after it (butt shifting, the body posture that precedes the lunging, etc.) Give her a stern "AHHH AHH! Stay!" and then praise when she does. The ultimate reward is the retrieve of the sent item...so let her have it as soon as she doesn't move and looks to you first for permission. She'll get it quick.