equanimity

equanimity \ee-kwuh-NIM-uh-tee; ek-wuh-\, noun:

Evenness of mind; calmness; composure; as, "to bear misfortunes with equanimity."

For one whose mind has been notoriously troubled, Brian Lara is at least retaining a sense of equanimity.
-- Richard Hobson, "Croft offers no respite as Lara's theme continues", Times (London), June 8, 2000

When one is happy, one can look at both comedy and tragedy with equanimity.
-- Phillip Lopate, Totally, Tenderly, Tragically

I think one person can hardly understand why another has conducted his life in such a way, how he came to commit certain actions and not others, whether he looks upon the past with mostly pleasure or equanimity or regret.
-- Chang-Rae Lee, A Gesture Life

Equanimity comes from Latin aequanimitas, "impartiality, calmness," from aequanimus, "impartial, even-tempered," from aequus, "even" + animus, "mind, soul."