William spoke candidly about the royal family's major health scares, saying 2024 has "probably been the hardest year in my life" and a "dreadful" experience.
The princess has talked about her cancer journey, describing in a video how the episode had been "incredibly tough for us as a family", but this is the first time the prince has revealed his thoughts in detail.
When asked about his year, William replied: "Honestly, it's been dreadful. It's probably been the hardest year in my life.
"So, trying to get through everything else and keep everything on track has been really difficult.
A message from Catherine, The Princess of Wales— The Prince and Princess of Wales (@KensingtonRoyal) As the summer comes to an end, I cannot tell you what a relief it is to have finally completed my chemotherapy treatment.The last nine months have been incredibly tough for us as a family. Life as you know it can change in an… pic.twitter.com/9S1W8sDHULSeptember 9, 2024
"But I'm so proud of my wife, I'm proud of my father, for handling the things that they have done.
"But from a personal family point of view, it's been, yeah, it's been brutal."
Kate appeared in a deeply personal video with her family in September to confirm her return to public duties following the completion of a course of chemotherapy.
The princess's heartfelt message about her cancer journey was spoken over images showing the Waleses and their children enjoying the outdoors, and she said her focus now was "doing what I can to stay cancer-free".
The King's cancer diagnosis was announced in February and he has been receiving treatment for an undisclosed form of the disease as an outpatient, but will be returning to fuller duties and greater overseas travel next year.
The prince's comments were made in an interview with British media covering his four-day visit to South Africa, which ended on Thursday, to stage his Earthshot Prize in Cape Town.
Prince William has wrapped up his visit to South Africa to stage his Earthshot Prize in Cape Town. (AP PHOTO)
When told he appeared relaxed, the prince replied: "I couldn't be less relaxed this year."
It appears his work recognising environmental entrepreneurs with the Earthshot Prize or trying to find solutions to end homelessness have provide an antidote to his tough year.
"It's more a case of just crack on and you've got to keep going," he said.
"I enjoy my work and I enjoy pacing myself, and keeping sure that I have got time for my family too."
William staged his Earthshot Prize ceremony in an eco-dome on Wednesday night and in a speech to guests dubbed his environmental awards as a "movement for change", and called on the world to join.
The event had five category winners awarded Stg1 million ($A1.9 million) each to develop their ideas to "repair" the planet.
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