“Physiologically, kindness can positively change your brain. Being kind boosts serotonin and dopamine, which are neurotransmitters in the brain that give you feelings of satisfaction and well-being, and cause the pleasure/reward centers in your brain to light up. Endorphins, which are your body’s natural pain killer, also can be released.  It is not just how you treat other people — it is how you extend those same behaviors and intentions to yourself as well.”

MAYO CLINIC