More and more researchers are finding that gratitude doesn't just make you feel like a better person, it's actually good for your health. Professor and researcher Robert A. Emmons puts it this way: "Clinical trials indicate that the practice of gratitude can have dramatic and lasting effects in a person's life. It can lower blood pressure, improve immune function and facilitate more efficient sleep."

One recent study from the University of California San Diego's School of Medicine found that people who were more grateful actually had better heart health, specifically less inflammation and healthier heart rhythms. They showed a better well-being, a less depressed mood, less fatigue, and they slept better. Gratitude has the opposite effect of stress.

Another study found that gratitude can boost your immune system. Stressed-out law students who characterized themselves as optimistic actually had more disease-fighting cells in their bodies. And in another study people who keep a gratitude journal have a reduced dietary fat intake—as much as 25 percent lower. Stress hormones like cortisol are 23 percent lower in grateful people. And having a daily gratitude practice could actually reduce the effects of aging to the brain.