Let us live in such a way that our happiness is beneficial to the whole world.

Anyone who lives with someone else knows what a bad day at work does to a kitchen. It arrives ahead of the person, and everybody adjusts around it for an hour.

The reverse travels just as fast and gets noticed far less. Someone in a decent mood is patient with a slow cashier, and the cashier is then slightly kinder to the next twelve people, none of whom will ever know why.

That is the entire mechanism. No grand scheme required. Your mood is not a private matter. It is the weather everyone near you has to live in today.