Both come back to the same thing.

Happy men are enthusiastic and energetic. Enthusiasm and energy eventually turns into a positive act and any positive act improves and builds up a man. The happy man grows and the ugly debbie downer keeps fermenting his soul away in their negativity.

The ugly debbie downer passes the happy man on the street and the ugly debbie downer is instantly reminded of his own character faults than prevent them from becoming the happy man they just passed.