According to a psychologist, fine weather and the prospect of some time off work helped make Friday the happiest day of the year.
Dr Cliff Arnall, specialist in seasonal disorders at the University of Cardiff, devised a formula to work out when Britain would hit a national hight point.
He used the equation: O + (N x S) + Cpm divided by T + He, which takes six different variables into account.
He used a similar formula to work out that January 24 was the most depressing day of the year.
The six variables in the happiness equation are: O for being outdoors and outdoor activity; N for nature; S for social interaction; Cpm for childhood summers and positive memories; T for temperature; and He for holidays and looking forward to time off.
Lower summer fuel bills and a post-general election sense of "renewal" are also said to improve the nation's mood.
Even the start of Wimbledon adds as a national pick-me-up by giving us fresh hopes of a British winner, according to the research commissioned by Walls.
Friday was finally pin-pointed as the happiest of the year because it is a - Friday.
Dr Arnall said: "Happiness is associated with many things in life and can be triggered by a variety of events.
Whether it's a sunny day, a childhood memory, or something as effortless as eating a delicious ice cream - I wanted my formula to prove the key to happiness can really be that simple."
The formula was commissioned by Wall's Ice Cream to help the company analyse the factors associated with happiness and key ice cream eating moments.