HIRE SUNNY! FIRE GLOOMY! Q.E.D.
Hire/Promote those with ... Sunny Dispositions.
Fire those with perpetually ... Gloomy Dispositions.
(Hint: The farther Up the Organization you go, the more important this gets.)
(Rule: Leaders are not permitted to have "bad days" ... especially on Bad Days!)
(Rule: One Sad Dog can Infect a group of 100.)
(Rule: One Energetic, Optimistic, Sunny Soul can motivate an Army to Move a Mountain.)