It is said that happiness should be attained from the "inside out". That it

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It is said that happiness should be attained from the "inside out". That it should be unilaterally seeked, and not externally determined. On a philosophical standpoint, is this view tenable, considering that we do not live in a vacumn? It is, to a large extent, true that we can choose the way we respond to a situation. But wouldn't undesirable or negative events (or even harassment) trigger the need to choose to respond in a way that does not allow for the event to determine one's happiness, and that that itself connotes that external events have a role to play? I may be stretching the notion too far, in which case, a rephrasing of the question would involve asking the extent to which happiness should/could be unilaterally determined? On a general level, is happiness a concept that is consensually determined (a social construct) or is it a subjective pursuit, such that one can "choose to be happy" for real?