It may be to do with the two types of validation we like. The first is external validation, so we look to others for postive comments and actions that tell us we are popular that day. Unfortunately if people are critical or ignore us or are rude that day.....we have a shite day! So that is not a good way to validate ourselves - better to work on relying on ourselves to validate what we are, do and think. That way we can have a good day every day, and encourages us to be kind and fair, because otherwise our opinion of ourselves plummets and the price of that is high.
Serotonin kicks in