Lanchester, in his piece on the pursuit of happiness, refers to a “happiness formula”, which I developed along with Ken Sheldon and David Schkade. In this “formula” – a reductive term that we never used – three primary factors determine happiness: your genetically based “set point”, the circumstances of your life, and the intentional activities or behaviors you engage in… Beyond the interpretation of “voluntary” that Lanchester focusses on (and dismiss as obvious) – that of nurturing relationships – we also looked at a more nuanced range of intentional behaviors, including expressing gratitude, practicing optimism, and committing to life-long goals.