Short answers, pulled from the story.
Daniel Kahneman describes happiness as the experience of the present moment, which is the affective state that floods the mind right now. This definition focuses on the immediate, visceral reality of joy rather than long-term life satisfaction.
Jeremy Bentham proposed that happiness should be the primary goal of human existence and the metric by which governments are judged in the year 1780. He attempted to create a hedonic calculus to measure pleasure and pain for public policy.
Sonja Lyubomirsky estimated that 50 percent of a given human's happiness level is genetically determined. While some studies suggest heritability can range from 70 to 90 percent, the common consensus settles around 20 to 50 percent.
The Framingham Heart Study, which began tracking the health of residents in Framingham, Massachusetts, in 1948, revealed that a person's level of subjective well-being is determined by many social influences. A friend who lives within a mile and who becomes happy increases the probability that a person is happy by 25 percent.
Hedonism focuses on seeking pleasant and avoiding unpleasant experiences, while eudaimonia describes a life of meaning and purpose. Aristotle argued that the good life is the life of excellent rational activity, which fulfills human nature in an excellent way.
Harvard professor Daniel Gilbert coined the term synthetic happiness to describe the ability to create happiness for oneself even in the face of adversity. This concept relies on the psychological immune system to help people reinterpret negative events and find meaning in their experiences.