The date of the "new year" varies from society to society. For instance, the Jewish new year, Rosh Hashanah, is celebrated in the fall, while the Chinese New Year begins on the second new moon after winter solstice (late January to mid-February). Until 1753, England and its colonies rang in the new year on March 25, which coincided with a Christian holiday called Lady Day (the Feast of the Annunciation). They made the switch to January 1 when they converted from the Julian calendar to the Gregorian.
If you're making any difficult new year's resolutions this year, take heart: people have been struggling with them ever since the early Babylonians started the tradition. (Their most popular resolution was to return borrowed farm equipment, in case you were wondering.)