Cost: $0.00 — Day 2 Kindness Challenge

Day 2 of the Kindness is Free campaign. Today's act: give someone a genuine compliment. Not a reflex "nice shirt" — a real one you actually mean. It takes five seconds. It costs nothing. And the person receiving it will probably think about it for days.

Research on prosocial behavior consistently finds that givers underestimate how much a sincere compliment means to the recipient. We assume it'll be awkward or come across as odd. It rarely does. People are almost always quietly moved.

Pick anyone — a coworker, a neighbor, the person behind you in line. Notice something true about them and just say it out loud. That's the whole thing.

Today's challenge: Give one genuine compliment before the day ends.