The real sting of this observation lies in what it reveals about our self-deception: we nurse grievances while believing ourselves righteous, convinced we're punishing others when we're merely marinating in our own bitterness. Mandela speaks from hard-won authority—twenty-seven years in a cell gave him intimate knowledge of how resentment corrodes the person who carries it, not the person who wronged them. A manager who dwells on a colleague's betrayal finds her own work suffers, her health declines, her relationships with innocent parties grow sharp and suspicious; meanwhile, the colleague moves forward unbothered. The quote's power is that it doesn't ask you to forgive for *their* sake, but to recognize that your anger is a sentence you're serving.