For many of us, we conjure up the past not just to resolve an issue (which is often healthy and productive), but with a compulsive tendency to re-hash and re-live it because it irritated us (which is a waste of time). The mantra, when it’s over, it’s over, is a reminder to me that bringing up old issues, reliving an anger-provoking experience, or trying to remedy a situation that has come and gone doesn’t help.