Prince William and Harry express concern about their father Charles on his 70th birthday

As the Prince of Wales gets ready to celebrate his 70th birthday next week, his sons speak out about why they are worried about him.

In a recent documentary, Prince William said he is trying to convince his workaholic father to slow down and spend more time with his grandchildren.

Read more on our Twitter account, @amomama_usa. Prince William added that even though Prince Charles is the fittest man he knows, it's time to rest.

He added: "Now he’s reached 70, it’s a perfect time to consolidate a little, because as most families would do, you are worried about having them around."

William admits that "having more time with him at home would be lovely," and said Prince Charles is brilliant when it comes to his grandchildren.

At the moment, he has three grand tots – George, 5, Charlotte, 4, and six-month-old Louis – with a fourth one way from Prince Harry and Meghan.

Other members of Prince Charles's family also spoke out about the future king, including Prince Harry and the Duchess of Cornwall, Camilla.

She gave testament to what a wonderful grandfather Charles can be and added that everybody adores him:

"He reads Harry Potter, and he can do all the different voices, and I think children really appreciate that. He will get down on his knees and crawl about with them for hours, you know, making funny noises and laughing. My grandchildren adore him—absolutely adore him!"

The documentary about his life, "Prince, Son & Heir: Charles at 70," premiered on BBC One earlier this week.

During his royal visit to Ghana, Prince Charles talked about plastic pollution, explaining how the callous use of plastics is destroying the world.

Prince Charles met with environmentalists and activists in Accra, the capital of Ghana and discussed the plastic crisis with experts in the field.

He commended the effort of environmentalists to reduce plastic waste when he heard that more than 10 tons of plastic were collected at a workshop to be turned into art.