"I think it is nice to get older. I don’t think about my physical age," the mother of four told the newspaper Berlingske Tidende.
Mary, who was photographed with the family pet Ziggy, added: "At 40 years old you simply know what life is about. I am happy to continue with my journey through time."
The graceful royal isn't the only one in the family celebrating her birthday. Her sister-in-law Marie, who recently gave birth to her second child, celebrates her 36 birthday on Monday.
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