De Niro last took home an Oscar in 1981, for his portrayal of the real-life world middle-weight champion, Jake LaMotta, in 'Raging Bull', reported CBS News.
"I was surprised that it was so long. I can account for all the things and all the time, and everything, but there it is. It's like, so many years ago," he said.
In 'Silver Linings Playbook', De Niro plays Pat Solitano, Sr, an obsessive-compulsive, die-hard Philadelphia Eagles fan, who struggles to deal with his even more obsessive and mentally-unstable son.
This is the seventh Oscar nomination for the 69-year-old actor, who said he has been extremely lucky in his career to have achieved whatever he has.
"I'm lucky that I have whatever I had that makes me have a successful career, if you will... I'm lucky I have the drive to do the work. But you're always lucky," he said.