Will happier people return your lost wallet?
It is the UN's International Day of Happiness.
It follows the release, on Thursday, of the World Happiness Report which ranks the world's happiest countries by asking people to evaluate their lives.
Both the UK and the US slipped down the list to 23rd and 24th respectively - the lowest-ever position for the latter.
But it's not miserable for everyone in the UK - Belfast is the happiest place in the country, according to the Office for National Statistics.
Why? Because people in towns and cities that would return a lost wallet, are the cheeriest places.
Mark Easton went to Belfast to test the theory.
Read more on which countries rank highest in the happiness report
