On 28th June 2012 the United Nations proclaimed 20th March as the International Day Of Happiness.
This was in recognition of the relevance of happiness and well-being as a universal goal and aspiration in the lives of Human Beings around the world, conscious that the pursuit of happiness is a fundamental human goal.
I think their choice of day was admirable as end if Winter and beginning of Spring brings the nature around us to a lively beauty, giving us more cause and opportunity for being happy.
This is a link to the UN website where you can find the resolution they adopted in their General Assembly of 28/06/2012.