From World Happiness Report 2022
From World Happiness Report 2022: The most consistent finding with respect to the brain areas involved in well-being is that a more active default mode network (DMN) is related to lower well-being. (The DMN is a large brain network primarily composed of the medial prefrontal cortex, posterior cingulate cortex/ praecuneus, and angular gyrus). This network is most active when a person is not focused on the outside world, and the brain is at wakeful rest, such as during daydreaming and mind-wandering
— from Time