Don't come running every time she asks you to do something, like put new batteries in a toy, says Lonna Corder, director of the Playgroup, a Montessori school in San Francisco. "Say, 'I can't do that right now,' so she doesn't get hooked on immediate gratification," she recommends.
Praise your child when she holds her horses. It'll reinforce the behavior.
Do projects together that require patience. For example, sprinkle grass seeds over moist soil in a cup, cover it with plastic wrap, and set it on a sunny window sill, Corder suggests. In a few days, your child can enjoy the sprouts.
Break out a sand timer occasionally. If your child's taking turns on the computer with her brother, it'll give her a visual of how the time is passing.
Deliver on promises. Don't say you'll take her to the park after lunch, and start the laundry instead. "Your child needs to trust that if she waits, you'll come through," Polson says.