The culmination of the Brahma Viharas, the ten paramis, and the factors of awakening. Equanimity allows us, like the Buddha, to 'sit in the middle'. Moment to moment mindfulness brings balance and openness to meet our joys and sorrows.
The distortion of delusion operates in many ways, including when we are disconnected from our direct experience, or only allow in information that doesn't challenge our deluded state of mind. Learning how to recognize when delusion is distorting our experience allows us to wake up out of its spell and discover clarity and peacefulness.
By welcoming joy we become content, so we relax, thus letting go of the need to do something - anything about it - thus calming down. Inner and/or outer joy facilitates the shift from doing to being - from trying to letting go - crucial steps on the path to awakening.