"There was a point in my life where I was really down, really confused, I didn't know what was going to happen and I thought 'I should be a director!'. And so I did it, and I worked very hard," Affleck said late Saturday as he received the award for outstanding directorial achievement in feature film from the Directors Guild of America.
"I worked really really hard to try to become the best director that I can be," Affleck added. "I don't think that this makes me a real director but I think it means I'm on the way."
The award was presented to the 40-year-old director by last year's winner, French director Michel Hazanavicius, whose film "The Artist" had been crowned by five Oscars.
Usually, the winner of the DGA prize also wins the Oscar for best director, but Affleck has not been nominated for an Oscar in this category.
"Argo" itself however has received seven Oscar nominations, including best picture.
Also competing for the top director's prize on Saturday were Steven Spielberg for "Lincoln," Kathryn Bigelow for "Zero Dark Thirty," Tom Hooper for "Les Miserables" and Ang Lee for "Life of Pi."
"Argo" also won the top Golden Globe awards against all the odds, beating "Lincoln."
The film has emerged as a leading rival to "Lincoln" at the Oscars, which take place on February 24 in Los Angeles.
Other DGA award winners include Lena Dunham for television comedy series "Girls," and Malik Bendjelloul for "Searching for Sugarman," the most award-winning documentary of the season.
DGA also honored Jay Roach for his movie "Game Change," which had already won the Emmy and Golden Globe awards for his brilliant portrayal of ultra-conservative Republican vice presidential candidate Sarah Palin -- played by actress Julianne Moore -- during the US presidential campaign of 2008.