Celebrating your 100th birthday means an awful lot of candles to blow out but more excitingly, a special message from the Queen.
People up and down the country place their cards from Her Majesty in pride of place if they are lucky enough to reach the landmark occasion.
But it turns out the Queen is always a bit worried that the cards she sends out, which she signs herself, don't always make it.
She revealed the concern during a chat with a 100-year-old "Dambuster" on her first public engagement since returning from Balmoral this afternoon.
She visited the Haig Housing development near Morden, south London, to officially open the charity's 70 new homes for veterans and their families.
On her visit she met veteran, Ken Souter, 100, who flew with the RAF in north Africa during the Second World War.
The centenarian, who also flew one of the four Lancaster bombers in the 1954 Dambusters film, showed the Queen the telegram he received on his 100th birthday.
The Queen said she was "glad to see" the card had arrived, as she is "always worried" the post will not be delivered on time.
She also met Invictus Games silver medallist Dan Phillips, who called the day an "absolutely incredible experience".
Mr Phillips, who uses a wheelchair after being injured in Afghanistan in 2012, previously met the Duke of Sussex during trials for the Invictus Games in 2017.
His son, Harry, then two, was caught on camera having a boxing match with the Duke, as his Dad fought to qualify for hand-cycling, indoor rowing, powerlifting and archery.
Mr Phillips said after Friday's event: "I was a young lad that grew up on a council estate, snotty nose, holes in my shoes... For somebody like that to get to meet the Queen is brilliant."
The Queen also chatted to a number of veterans who completed a 100-mile walk from Ypres to London - The Long Walk Home - last year, to mark the centenary of the Armistice.
She has been patron of Haig Housing since 1952 and was handed dozens of bunches of flowers and greeted by hundreds of local schoolchildren during her hour-long visit.
The Queen was even given a laugh when one child shouted "you're the best Queen in the world" as she greeted the crowds.
The monarch wore a cornflower blue dress and coat from designer Angela Kelly, alongside a matching hat.
Haig Housing is the country's largest military housing charity, with more than 1,500 properties across the UK.
The site in Morden first opened almost 100 years ago, following the end of the First World War.
The charity offers the opportunity for the most seriously injured veterans to get onto the property ladder and become joint owners of homes that have been specially adapted to suit their needs.
