Gratitude is an action word as well as an attitude. You practice gratitude when you make a list, when you go out of your way to help a stranger in need, or when you donate to a charity. Real gratitude is practiced when it is truly an "act of kindness"; not simply filling in the "gratuity" line when signing a credit card receipt at a restaurant.
Cortisol production (the 'stress' hormone), and the entirety of the autonomic nervous system is a hot topic when it comes to yoga. We delve deeper to discover that cortisol is both raised AND lowered, activating both the sympathetic nervous system (SNS) and parasympathetic nervous system (PNS).