Smiling stimulates the release of substances such as dopamine, serotonin and endorphins, neurotransmitters that help increase the feeling of well-being, and reduces the levels of cortisol, a hormone that is secreted in response to stress and anxiety. Therefore, a kind of virtuous circle is generated: feeling good makes you smile, and the same smile increases the feeling of wellbeing. It's as if the smile and happiness feed themselves.