What keeps Prince Philip hale and hearty at the age of 99?

Royal fans are counting down days till Prince Philip marks his 100th birthday in June this year.

And while the big day of the Duke of Edinburgh is being awaited by members of the British royal family as well as fans, some royal aides are unveiling the secrets of the 99-year-old’s healthy lifestyle.

Speaking to Hello! magazine, royal doctor Anna Hemming said: “Keeping active both physically and mentally play a very important role in maintaining a healthy and ongoing quality of life.”

“Sport has its benefits in keeping both your body and mind active. When the time comes to retire from sport the interest in sporting activities helps to stimulate your mind,” she went on to say.

As reported by Express, international horse-riding federation FEI claims that the duke has been a “keen sportsman throughout his life” by playing cricket, hockey and rowing.

“Like all other people who lead a fit healthy life and enjoy a balanced intake of healthy food, they are more likely to enjoy a more healthy quality of life in their later years,” she continued.

Prince Philip’s diet is almost made up of the best power-packed foods, including eggs, smoked haddock and omelet.