Kindness is one of the most undervalued commodities — which is too bad because, as you discovered, it doesn't take much of it to turn the day around. I wonder if we overlook kindness because it's so simple. What's really involved? Someone needs something, we help. Someone feels low, we console. Someone trips, we catch them. There's a need, we respond. Then the other person is grateful and relieved — and we're happy knowing we could help. Kindness is a low-effort, high-return exchange.

Joan Duncan Oliver, Happiness: How to Find It and Keep It