Kit Harington absolutely HATES that he was born on Boxing Day, but ya can't hate on him for squaring up like a champ in the ring.
The "Game of Thrones" star worked up a sweat at a gym Thursday in NYC ... where he was attending a boxing class with a buddy, but clearly the spotlight belonged to him. Kit -- aka Jon Snow -- started off looking like a newbie but didn't take long before finding his rhythm.
Check out the pics and this vid ... his right hook's got potential.