Maybe you don't like your job maybe you didn't get enough sleep well nobody likes their job nobody got enough sleep. Maybe you just had the worst day of your life but you know there's no escape there's no excuse so just suck up and be nice.
My pet peeve and my goal in life is to somehow get an adjective for 'integrity' in the dictionary. 'Truthful' doesn't really cover it or 'genuine.' It should be like 'integritus.'