The centre-forward was roundly criticised for his performances in his home tournament, most notably in his side's humiliating 7-1 defeat to eventual winners Germany in the semi-final.
Fred has since retired from international football, and he has admitted that it has taken him a while to recover from the disappointing experience.
"It's now in the past," Xinhua quotes Fred as saying. "The responsibility during the World Cup was huge and unfortunately things didn't turn out.
"It's a part of football. I knew that it was going to be a long process. It was a heavy load to bear but I'm getting over it."
Fred was speaking after his two goals had helped Fluminese to a 3-0 victory over Palmeiras.