There was reportedly a time when Prince William had dreams of building a career in the military but he was forced to give up on this because of his grandmother. 

In his younger years, Prince William wanted to pursue a life of service as a military man. He had dreams of scaling the ranks in the Armed Forces but Queen Elizabeth asked him to give this up for a very important reason. 

The Duke of Cambridge is the second in line to the British throne. He grew up knowing that he will be carrying a huge responsibility as the future King of England one day.  

Yet he still wanted to pursue a career in the military and signed up to be a helicopter pilot. According to Simon Vigar in the documentary William and Kate: Too Good to be True, the Duke of Cambridge was actually "desperate" to keep a job in the frontlines.

However, his grandmother put her foot down and told William that this kind of job is not for him. While the Duke of Cambridge wasn't able to use his flying skills in combat, he did become a helicopter pilot for the emergency services for the Royal Air Force in Anglesey. 

Prince William flew a yellow helicopter for a couple of years and helped the rescue team save many lives in medical emergencies in the British Isles. He later also became an emergency services pilot for the East Anglian Air Ambulance.

By 2017, however, Prince William quit being a pilot to join Queen Elizabeth and perform his royal duties full-time for the Crown. He and his wife, Kate Middleton, the Duchess of Cambridge, are now seen as significant members of the Firm and bright future of the monarchy.

Royal journalist Jeremy Paxman said in his conversations with Princess Diana years ago that William used to confess to her that he doesn't want the job of the king. Part of the reason he's not thrilled to be the top man in the royal family is because his father, Prince Charles, has to die first before he assumes the throne. His grandmother also has to pass away before Prince Charles takes over. 

However, this is the reality of the line of succession in the British royal family. While it might seem like Prince William has been hesitant about his future role, the Duke of Cambridge has been learning to embrace his destiny in the last few years. Prince William is finally learning to understand the meaning of duty and why, after all these years, her grandmother remains dutiful to the Crown.