Speaking at the launch of "The Class Of 92", David Beckham said he is surprised "everyday" at how his life has turned out.
Dozens of people queued to get their hands on clothing and shoes donated by Victoria and David Beckham at the British Red Cross in Chelsea.
Collection includes shoes by Jimmy Choo and suits by Dolce and Gabbana alongside tops, suits, trainers and dresses.
Former England captain David Beckham has paid tribute to Nelson Mandela, whom he met while on international duty in South Africa in 2003.
Writing on his Facebook page, Beckham said: "My heart goes out to the people in South Africa and Mr Mandela's family.
"We have lost a true gentleman and a courageous human being. It was truly an honor to have known a man who had genuine love for so many people. Rest in peace."
The film examines the difficult period in Beckham's life after he was sent off at the 1998 World Cup.
"There will be a few tears in there from my mum I'm sure," Beckham said.
The former England captain said he valued the support of his teammates throughout tough moments of his career.
"It's the same for all of us six. There were good times, there were bad times, there were troubled times where we all stuck together," he said.
"But that is part of the movie, part of the history of the six of us.
"That is why it makes this such a great story."
Class of '92 stars David Beckham, Paul Scholes, Nicky Butt, Ryan Giggs and Phil and Gary Neville arrived at the documentary's premiere at Leicester Square.
The former England captain attended the event with wife Victoria, and the couple's three sons Brooklyn, Romeo and Cruz.
When asked about reports that Beckham could become Sir David in the New Year Honours List, Styles replied: "Why not? He's a national treasure isn't he? It makes sense. I thought he was already."
Victoria Beckham said she had "so much fun" guest editing Vogue Paris' Christmas issue and gave her Twitter followers a sneak peek at the two front covers.
Vogue says the issue "transports readers straight into the world of Victoria Beckham" with the help of an interview, anecdotes, family photos and even some drawings by her children.
The front covers both feature Victoria and David Beckham and were shot by photographers Inez and Vinoodh.
Vogue Paris described the Spice Girl-turned-designer as "a fashion superstar on the New York scene", adding, "She's built a global business empire, never failing to build on her success wherever life has taken her".
Items donated by the Beckhams for the charity auction in Chelsea are being sold on ebay. A pair of Victoria Beckham's D&G shoes had a starting bid of 99p.
Clothes donated by David and Victoria Beckham have gone on sale at a charity shop in southwest London, including a wall filled with designer shoes.