LONDON (AP) — Queen Elizabeth II has reluctantly accepted medical advice to rest for a few days and has canceled a trip to Northern Ireland, Buckingham Palace said Wednesday.

The palace didn't offer specifics on the decision, but says the 95-year-old monarch is “in good spirits,'' and disappointed that she will no longer be able to visit Northern Ireland for engagements Wednesday and Thursday.

“The Queen sends her warmest good wishes to the people of Northern Ireland, and looks forward to visiting in the future,'' the palace said.

She is resting at Windsor Castle, where she has stayed since the onset of the COVID-19 pandemic last year. The decision to cancel the trip was understood to not be COVID related.

The decision comes just days after Elizabeth was seen using a walking stick at a major public event when attending a Westminster Abbey service marking the centenary of the Royal British Legion, an armed forces charity.

She had previously been photographed using a cane in 2003, but that was after she underwent knee surgery.

Britain’s longest-lived and longest-reigning monarch, Elizabeth is due to celebrate her Platinum Jubilee — 70 years on the throne — next year.

The queen, who was widowed this year when Prince Philip died at age 99 in April, still keeps a busy schedule of royal duties. On Tuesday, she held audiences with diplomats and hosted a reception at Windsor Castle for global business leaders.

Despite her great age, the monarch has politely declined the honor of being named “Oldie of the Year” by a British magazine. The Oldie magazine on Tuesday published the queen’s response to its suggestion that she follow in the footsteps of former recipients, such as actor Olivia de Havilland and artist David Hockney.

“Her Majesty believes you are as old as you feel, as such The Queen does not believe she meets the relevant criteria to be able to accept, and hopes you will find a more worthy recipient,” said a letter from her assistant private secretary, Tom Laing-Baker. He ended the letter “with Her Majesty’s warmest best wishes.”

Danica Kirka, The Associated Press