King Charles III celebrates his 76th birthday on Thursday, continuing to serve as Britain’s head of state despite a year marked by health challenges and personal hardships.

Still undergoing cancer treatment, the King’s commitment to his royal duties remains unwavering, as he defies the physical toll of his illness, with his son and heir, Prince William, describing this year as “brutal.”

The monarch, who paused his official duties in February after a cancer diagnosis, returned to public service at the end of April, resuming his duties with renewed vigour. "The problem is trying to stop him," remarked Queen Camilla, his wife, on multiple occasions, highlighting Charles’s relentless drive.

In recent weeks, King Charles and Queen Camilla resumed their international travel, visiting Australia and Samoa for a Commonwealth Heads of Government meeting. Sources close to the royal couple revealed that the King returned “invigorated” from the 11-day trip, with plans to continue his overseas engagements in the coming year.

Having ascended the throne following the death of his mother, Queen Elizabeth II, in September 2022, King Charles had already made history as the longest-serving heir apparent in British history, having waited 70 years to take the throne. Despite the challenges of his health, he remains committed to fulfilling his constitutional role “throughout the remaining time God grants me,” as he pledged during his accession.

This past Sunday, Charles led the nation in a poignant two-minute silence at the Cenotaph memorial in London, a key moment in the national calendar, commemorating British service members who have lost their lives in battle since 1914. The day before, he attended a commemorative concert at the Royal Albert Hall with his son, Prince William, and daughter-in-law, Princess Catherine, who had recently completed chemotherapy for her own cancer treatment.

The King’s birthday will be marked by ceremonial gun salutes, a long-standing royal tradition. However, he will not have the day off; instead, he is set to attend the opening of a food redistribution centre in south London, which is part of his “Coronation Food Project” aimed at tackling food waste and supporting vulnerable communities. This initiative, launched on his 75th birthday, is close to his heart, and he will inspect a newly installed industrial freezer at the facility.

It has been a particularly testing year for the royal family. King Charles’s relationship with his younger son, Prince Harry, and his wife Meghan remains distant, while both Charles’s and Prince William’s financial matters were the subject of controversy following recent allegations aired in a documentary. Additionally, discussions about reparations for Britain’s colonial past gained traction during the Commonwealth summit earlier this year.

However, it is the health issues within the family that have dominated headlines. Following his prostate operation, Buckingham Palace confirmed that the King had been diagnosed with cancer, though the specific type has yet to be disclosed. His wife, Queen Camilla, also experienced health setbacks this year, with a lung infection forcing her to cancel several engagements.

In March, Princess Catherine, who is widely admired for her public presence, revealed that she too had been battling cancer, though the details of her diagnosis remain private. After completing her chemotherapy, Catherine shared a heartfelt message on social media in early September, which was met with widespread praise. She has since gradually resumed her royal duties, much to the relief of her supporters.

Prince William, speaking candidly earlier this month during a visit to South Africa, acknowledged the emotional strain on the family. "Honestly, it’s been dreadful. It’s probably been the hardest year in my life," he said. "But from a personal family point of view, it’s been, yeah, it’s been brutal."

The royal family’s health remains under close scrutiny, and recent trips have been carefully managed to ensure their well-being. A doctor accompanied the King and Queen on their trip to Australia and Samoa, and on their return journey, they spent several days at a wellness retreat in India. However, the King was forced to cancel his planned trip to Baku, Azerbaijan, for the COP29 climate summit due to health concerns.