"Adults who frequently feel grateful have more energy, more optimism, more social connections and more happiness than those who do not, according to studies conducted over the past decade. They're also less likely to be depressed, envious, greedy or alcoholics. They earn more money, sleep more soundly, exercise more regularly and have greater resistance to viral infections.
Now, researchers are finding that gratitude brings similar benefits in children and adolescents."
I would have to imagine they also volunteer more too! :)