Prince Philip just recently celebrated his 99th birthday in Windsor Castle with Queen Elizabeth II. While the celebration was not entirely disclosed before the public, royal fans and supporters shared their greetings toward the Duke of Edinburgh, as well as several members of the British Royal Family.

After his marriage to the then-Princess Elizabeth, he became a very active working royal until his retirement in 2017. Since then, he has stayed in Norfolk to relax and spend his days behind the royal scene.

With this at hand, several individuals, reportedly, wonder how the royal has able to reach his age in good health. Despite the numerous hospital visits in the past years, he, reportedly, remains in good spirits and health, even amid the pandemic crisis.

Prince Philip has a "sporty background," according to Hello! magazine. This has reportedly become an "advantage" for the Duke of Edinburgh in maintaining his health over the years.

Expert, Dr. Anna also, reportedly, explained that sports offer benefits in keeping the "body and mind active." It plays a "very important role" in maintaining one's health and "quality of life, she added.

Alongside his diet, another aspect being looked upon is the Duke's diet. As stated, he shares the same healthy and keen diet with his wife, Queen Elizabeth II. This is why it is not surprising why they have both remained healthy, as per reports.

Queen Elizabeth II and Prince Philip, reportedly, follow a "healthy, balanced diet." The Duke of Edinburgh, "in particular," is a "keen foodie," the reports said. As revealed, he has always taken over several dinner preparations to cook for himself.

In the popular book, Dinner at Buckingham Palace, former royal aide, Charles Oliver said that the Prince Consort's diet mainly focused on "protein-packed dishes." These include scrambled eggs, omelet with bacon, and smoked haddock, the former aide added.

Prince Philip is currently staying inside Windsor Castle with his wife, the Queen of the United Kingdom. He recently relocated to the Berkshire property following the pandemic crisis' emergence in the country.

As they continue to observe social isolation, he and Queen Elizabeth II marked the Duke's 99th birthday in private. While the details of the celebration have remained undisclosed, the royal couple released an official photo for the royal's celebration, according to the Daily Express.

As revealed, the photograph was taken on June 1 on the grounds of the castle. It also, reportedly, "echoes" the photo that they had on their 70th wedding anniversary in 2007.