Alex Korb writes in “The Grateful Brain,” “Gratitude can have such a powerful impact on your life because it engages your brain in a virtuous cycle. Your brain only has so much power to focus its attention. It cannot easily focus on both positive and negative stimuli.” Literally, you can’t be grateful and anxious at the same time. Once again, the threat system in our amygdala is overridden. On top of this, research shows gratitude stimulates the hypothalamus, a part of the brain that regulates anxiety.