The Queen quoted Groucho Marx's dictum on ageing in a speech at a lunch to celebrate her official 80th birthday.
Politicians joined members of the Royal Family earlier at a national service of thanksgiving at St Paul's Cathedral.
The Archbishop of Canterbury praised the Queen in his sermon, saying a "common loyalty to the monarch" had helped keep the country together.
The Queen credited US comic Marx in her speech saying: "Anyone can get old; all you have to do is to live long enough".
Speaking at Mansion House in the City of London, she also referred to the World Cup when she said: "Creating a good menu is a familiar dilemma for any host, but the solution of competitive cooking is a new concept to me - although I understand there are as yet no penalty shoot-outs."
Top chefs had competed in a BBC programme to create the lunch menu for The Queen and the 350 guests.
The Queen added: "There are in my view many other anniversaries this year which are more deserving of celebration.
"I hope you will permit me to single out two for mention: the 50th Anniversary of The Duke of Edinburgh's Award and the 30th Anniversary of The Prince's Trust.
"Both organisations in their different ways have changed - and continue to change - countless people's lives for the better."
She went on to thank the many thousands of people from the UK and all over the world sent her letters and cards.
The speech was made available as a podcast for MP3 players through the Royal Family website.
More than 30 members of the Royal Family, including Princes William and Harry, were at St Paul's Cathedral for the service.
Prime Minister Tony Blair and faith leaders joined a congregation of around 2,300.
Princes Harry and William were at the service
Former Prime Minister Margaret Thatcher and celebrities, including pop stars Cliff Richard and Eric Clapton, were also among the guests.
Prayers were said for The Queen's devotion to duty, Christian faith and long years of public service.
In his sermon, Dr Rowan Williams said the monarchy had been a "way of keeping power human".
The Queen had been a "steady presence" in an "age of inhumanity of ideology and of myths of racial supremacy", he said.
Dr Williams said "the Holocaust and Stalinism and ethnic cleansing, fanaticism and terror and mass destruction" reminded us what a tough question it was to ask what gives cohesion to a society.
He said that among the things which achieved "such cohesion as we have" was loyalty to the monarch.
"We have seen something of a monarch who has shared the vulnerability of ordinary people, and that has been moving in itself," he said.
BIRTHDAY LUNCH MENU
Smoked salmon with blinis, woodland sorrel and wild cress
Pan-fried turbot with cockles and oxtail
Loin of roe venison with potato cake, roast roots, creamed cabbage and game gravy
Custard tart with nutmeg
"But more importantly we have been able to see a bit more clearly the personal depth of our monarch's faith."
The archbishop led thanks to the Queen and to Prince Philip "who has so devotedly supported you" and wished the couple many happy more years.
As the Queen arrived at the event a fanfare was sounded by the State Trumpeters of the Household Cavalry.
Mr Blair paid his own tribute at the lunch, offering the Queen his thanks.
"We salute you today, we wish you well and above all we wish you many happy, long years to reign over us," he said.
"Ma'am, on behalf of the whole of the country, thank you."
On Thursday evening, the attention moved to the Queen's husband, Prince Philip.
The massed bands of the Royal Marines performed a beating retreat on Horse Guards to mark the Duke of Edinburgh's 85th birthday which he celebrated last Saturday.
On Saturday - her official birthday - the Queen will attend the Trooping the Colour birthday parade.
The royal tradition of two birthdays dates back to the time when, if monarchs were born in winter, the weather was deemed unsuitable for outdoor events.