Prince William has broken royal fan's hearts with the latest story about his seven-year-old son Prince George.

Prince William revealed that Prince George got so sad while watching a documentary by Sir David Attenborough about the extinction of animals that they had to turn it off.

The Duke of Cambridge said George said to him: “I don’t want to watch this anymore,” The Sun reports.

“The most recent one, the extinction one, George and I had to turn it off, he got so sad about it.

“He said, ‘I don’t want to watch this anymore, why has it come to this?’

“He’s seven-years-old and he’s asking these questions. He feels it.”

Prince William spoke to Sky News to mark the launch of his environmental Earthshot Prize and said that his children usually love watching Sir David Attenborough's A Life On Our Planet documentaries, but this one was too much.

The dad-of-three said he had struggled with staying optimistic about the future of the environment, adding: “I think, to be perfectly honest, I’m struggling to keep the optimism levels going with my own children, and that’s really kind of like, an understanding moment.

“Where you kind of look at yourself and go, ‘Am I doing enough on this, are we really at this stage in life when I can’t be hugely optimistic and pleased that my children are getting so into nature?

“Because you kind of worry and dread they’re soon going to realise that we are in a very, very dangerous and difficult time in the environment and that as a parent, you feel you’re letting them down immediately.”

The sweet story comes after a video of the Cambridge children asking Sir David Attenborough questions about the environment, with Prince George asking which creature would become extinct next.

View this post on Instagram

We've got some questions for you, @DavidAttenborough… ️

A post shared by Duke and Duchess of Cambridge (@kensingtonroyal) on Oct 3, 2020 at 5:59am PDT

Sir David Attenborough assured him that we could act to save endangered species from becoming extinct.

The Earthshot Prize will hand over $1.81 million each year for a decade to five winners who build innovative projects that are designed to save the planet.

This can include green businesses, cities or even planet-saving people movements.

Speaking this morning, Prince William said we had 10 years to “fundamentally fix our planet”.

“This is me putting my stamp on what I can do in my position to really galvanise and increase the interest and tackle some of these issues and drive a decade of change to help repair the planet,” Prince William told Sky News.

This article originally appeared on Over60.