Queen Elizabeth was told to give up horseriding almost two months ago.
The 95-year-old monarch - who was hospitalised for a night last week - is a keen equestrian but was advised to take a break from her pursuit in early September after suffering "discomfort" in the saddle, and is believed to not have ridden since her summer break at her Balmoral estate in Scotland.
A source told The Sun newspaper: “She was in quite a bit of discomfort. She adores riding and it has been part of her ritual for most of her life.
"She has been extremely disappointed not to go riding since the beginning of September.”
But the queen, who is currently on "light duties" and can't even walk her beloved dogs, is hoping she'll be able to ride again after taking time to rest and recouperate.
The queen - who is the oldest and longest-serving head of state in the world - recently announced she won't attend the COP26 climate change summit in Glasgow after being advised to rest by her doctors.
The monarch was scheduled to attend the high-profile event in Scotland, but she cancelled her original plans after undergoing preliminary medical checks and will instead address the delegates "via a recorded video message".
Buckingham Palace said in a statement: "Following advice to rest, The Queen has been undertaking light duties at Windsor Castle.
"Her Majesty has regretfully decided that she will no longer travel to Glasgow to attend the evening reception of COP26 on Monday, 1 November.
"Her Majesty is disappointed not to attend the reception but will deliver an address to the assembled delegates via a recorded video message."
Last week, Buckingham Palace confirmed that the Queen had gone to hospital for "preliminary investigations", and she stayed overnight before being sent back home to Windsor.
A spokesperson said at the time: "Following medical advice to rest for a few days, The Queen attended hospital on Wednesday afternoon for some preliminary investigations, returning to Windsor Castle at lunchtime today, and remains in good spirits."
It's believed that the overnight stay was for practical reasons, and the monarch was back at her desk on Thursday afternoon and was undertaking light duties.