An attitude of gratitude not only boosts joy and general life satisfaction, it's also the single best predictor of good relationships, and benefits both sanity and physical health.
Gratitude has measurable beneficial effects on the mood neurotransmitters serotonin, norepinephrine and dopamine, inflammatory cytokines, immune function, blood pressure, blood sugar, testosterone (sex hormone), oxytocin (social bonding hormone) and cortisol (stress hormone).
Gratitude has also been linked to improved self-care, such as getting exercise, eating well and getting regular health checkups, leading to fewer health complaints and doctor visits.
Gratitude exercises such as writing down what you're grateful for and paying-it-forward results in neural changes that create a positive feedback loop, increasing your ability to experience gratitude in the future.
When journaling about gratitude, focus on the benevolence of other people, on what you have received rather than what's been withheld, and avoid comparing yourself to people you perceive to have more advantages.