Prince William has a "new sense of purpose" in protecting the planet now that he has children.
The 38-year-old royal - who has Prince George, 7, Princess Charlotte, 5, and 2-year-old Prince Louis with wife Catherine, the Duchess of Cambridge - has "always loved nature" but his family has given him added drive to do what he can to look after the natural world for future generations.
Speaking in the upcoming ITV documentary Prince William: A Planet For Us All - which will air next month - he said: "Now I have got George, Charlotte and now Louis in my life - your outlook does change. You want to hand over to the next generation, the wildlife in a much better condition.
"I always believe it is possible to give young people hope and belief that things can get fixed.
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"I have the belief that if we all work together, we can make a difference."
The documentary was filmed over two years and sees the Duke of Cambridge "champion global action on conservation and climate change".
It also includes a meeting with naturalist Sir David Attenborough, with William's wife Catherine admitting their children would be cross that they'd met the Blue Planet presenter without them.
Catherine told him: "The children were very upset that we were coming to see you and they weren't coming. They're massive fans of yours."
David said: "Kids know an awful lot about what is happening to the world."
Next month, William will make his first TED Talk appearance to discuss climate change with a virtual panel consisting of impassioned climate activists such as Al Gore, Jaden Smith, Chris Hemsworth, Mark Ruffalo, Yemi Alade and Don Cheadle.
The group will discuss how the world can tackle climate change and ensure a healthier future for the planet.