Resentment is a complex human emotion often triggered by injustice or betrayal. Psychologists link its persistence to 'ruminative thinking,' where individuals constantly dwell on past hurt. Neuroscience attributes this to 'negativity bias,' as the brain prioritizes negative experiences. While some hold onto grudges as a form of protection or a quest for justice, studies indicate that this emotional burden primarily harms the person carrying it rather than the offender. Chronic hostility can lead to sleep disturbances, anxiety, and strained relationships. To break free, experts suggest acknowledging these feelings, shifting focus to the present, and seeking professional support.