According to reports, the Queen - who is now 84 - is in need of an operation on her knees which could see her out of action for up to four months, and which will probably spell the end of her equestrian days.

Horse riding is known to be the Queen's favourite hobby and despite her incredibly busy schedule - which sees her out of the country for much of the year and often involved in several engagements per day when in the UK - she could often be seen making the most of her free time on the back of a horse.

She particularly enjoyed riding in the early morning, often around the ground of Windsor Castle.

Commenting on the news, the Daily Mail said: "The monarch is renowned for her good health, energy and dedication to her duties. Since taking the throne 59 years ago in 1952, she has carried out hundreds of royal engagements every year, including state visits abroad and countless ceremonies, investitures and walkabouts in front of flag-waving crowds."

Despite being forced to cut down on her equestrian activities, 2011 is set to be as busy a year as ever for the Queen, who is due to meet with US President Barack Obama in May and take a trip to Australia in the autumn.

As well as this, her own 85th birthday is in April, which will be closely followed by the wedding ceremony of the year, which will see her grandson Prince William marry long-term love Kate Middleton at Westminster Abbey.

While slowing down might be an inevitable part of getting older for most, some people may decide to do the opposite and become more daring with age.

This is certainly the case for pensioner Joan Bowkey, who recently jumped into the saddle and enjoyed her very first horse-riding lesson - aged 93. Joan, who lives in Binstead, on the Isle of Wight, could be an inspiration to horse lovers who do not want to sacrifice their equestrian hobbies as they get older.

Horse riding can be a fun activity for people of any age and as well as helping with fitness levels, regular horse riding can improve peoples' personal confidence and also help them learn how to take care of an animal.