WATCH | Prince William talks men's mental health - 'We're not robots, we must speak up'

Prince William let English footballers in on his vulnerable side and struggles with mental health during a talk for a BBC documentary which aired on Sunday.

The royal emphasised on the need to destigmatise mental illness, with the goal to get more people to open up about their challenges.

Speaking about his own experiences, he cited the death of his mother, Princess Diana, as the biggest contributor to his struggle with mental health. 

He said the loss left him with feelings he has since questioned. "I've thought about it a lot and I've tried to understand why I feel like I do, but I think when you are bereaved at a very young age, you feel pain like no other pain."

In 2017 William, Kate Middleton and Prince Harry launched Heads Together, a royal charity that focuses on mental health. 

He said while losing his mother was a tragedy, the loss brought him closer to people who have also lost loved ones but had not spoken about it due to the shame attached to mental illness.

He said he learnt during his interaction with these people that although they are silent, they long to speak to someone and share their stories. 

"When you talk to someone else, you can almost see it in their eyes sometimes - you can kind of pick it up quickly that they want to talk about it." 

William further encouraged British people to open up more, saying "we need to talk,we're not robots".