Oh my goodness, when my son JR smiles, it really does light up a room.
For new Moms, even if you are a 10th time Mom, when your baby finally smiles back at you and responds to your care, there can be nothing that makes you feel more alive, amazing, wonderful and joyful. These first smiles are just amazing, because, in his or her own way, your baby is saying "Thank you" for everything you do.
Just remember, their smiles are letting you know that no matter how much you might feel you are messing up or failing at mommyhood, your babies think you are the greatest thing since sliced bread, and wouldn't trade you for the world.
And, just when you think you are ready to trade your children in for a nap, they smile, and you realize, another cup of coffee sweetened with their smiles will get you through anything. Even no sleep.