January 1st is considered New Years Day in today's society. But this is a fairly new concept because up until the time of Julius Caesar, the Romans celebrated the New Year in March because it was the first month in the Roman calendar. However, January 1 marked the time when the Romans changed their governmental figures and new consuls were inducted into office. And, they had games and feasting to help celebrate the new officials. But, they still used March 1 as their official mark of the new year and had a festival to their god, Mars (God of War).
It was Caesar who changed the Roman New Year's Day to January 1 in honor of Janus, (God of all beginnings and gate keeper of heaven and earth). Janus was always depicted with two faces: One looking back to the old year (past) and one looking ahead to the new year (future). One of the customs in the festival honoring Janus was to exchange gifts and then make resolutions to be friendly and good to one another.
When Constantine ruled the Romans and accepted Christianity as their new faith, they kept the Festival of Janus as the New Years Day ( Not March as before) and turned it into a day of prayer and fasting and not parties etc. It was a day for all good Christians to turn over a new leaf. However, the Romans may have accepted January 1 and Janus as the New Year, but many did not accept the turning over a new leaf, prayer and fasting part of it.
However, even in 1582, Great Britian and the English colonies in America still kept March for the beginning of the year. (Spring as a beginning?) It wasn't until 1752 that Britian (and it's colonies) adopted the new Gregorian calendar and January 1 as the beginning of the year. But many Puritans in New England felt Janus was an offensive pagan god and chose to simply ignore January 1 as a New Years Day. Instead they just made the entire month of January as "The First Month" of the months.
And, today no one really considers January 1 a fasting day. Ironically, for many it is a major day of feasting on junk food and watching football games on television.
How did New Year's Resolutions all begin?
Once again, we go back to the wild and crazy parties of the ancient Romans. :) They indulged themselves in alcoholic and sexual excess as a way of acting out all the chaos that they hoped a new year would get rid of. So, the New Year's festival was a way to start over. By purging yourself of all this so-called excess energy and confessing your sins, there was a hope that you would be much better in the next year ahead.
Now, the Puritans never did approve of all this New Year's hoopla. So of course they went for this religious renewal of cleanse, purge, fast, confess idea. So they encouraged young people not to waste the new year on foolish things but to use it as an opportunity to make a good change in their lives for the good. So, like some Christians, they made New Year's vows or pledges focused on overcoming their own weaknesses, to enhance their god-given talents and to make them better citizens to others.
The custom of making New Year's Resolutions came into vogue in the 20th century. But most of it was done with jest and an understanding that they would not be kept (for long anyway) since humans were naturally backsliders by nature to their naughty habits and ways.
The resolutions today are simply a secular version of the religious vows made in the past toward spiritual perfection. They are often made with good intentions and broken with a sense of humor and renewed annually.