(CNN) -- Britain's Prince Harry has revealed a secret.
The fourth in line to the throne unveiled a hidden fear Monday in support of the #FeelNoShame campaign being run by his Sentebale charity for World AIDS Day.
Prince Harry co-founded the Sentebale charity with Lesotho's Prince Seeiso in 2006 after being struck by the impact of AIDS/HIV on children and young people in the southern African nation.
Throughout the day, celebrities including singer Joss Stone, actor Charley Boorman, race car driver Daniel Ricciardo, and former rugby player and sport commentator Will Greenwood will be revealing secrets about themselves as part of #FeelNoShame.
Television presenter Luke Franks has already revealed that he sometimes wears ladies' jeans -- for a better fit -- while footballer Christian Eriksen admitted eating all his advent calendar chocolates early.
Wearing the red ribbon of the AIDS awareness campaign, Prince Harry revealed his secret in a video message released at 1 p.m. GMT.
"My secret is -- believe it or not -- I get incredibly nervous before public speaking, no matter how big the crowd or the audience and, um, despite the fact that I laugh and joke all the time I get incredibly nervous, if not anxious, actually, before going into rooms full of people when I'm wearing a suit," he said. "And now that I've confessed that, I'll probably be even more worried that people are looking at me."
World AIDS Day has been held every December 1 since 1988 and is aimed at increasing awareness of the virus and raising funds to combat its effects.
Prince Harry earlier posted a message on YouTube on behalf of Sentebale to mark World AIDS Day in which he said the virus was the No. 1 cause of death across Africa and second highest cause of death globally for those aged 10 to 19.
"One tragic issue in particular is the shame and stigma linked to HIV," he said. "This causes thousands of children to needlessly die each year because they're keeping their illness a secret and not getting the medical attention that they need."
He said Sentebale encouraged children to talk openly about their health concerns.
"To show our support to the children of Lesotho and help reduce the stigma for all those affected by HIV, we are turning this World AIDS Day into a day in which no one should feel any shame about their secrets," Prince Harry said.
"Myself and many others will be sharing secrets of our own throughout the day and we ask everyone else to do the same. Please use the hashtag #FeelNoShame to share your secret on social media and show the children of Lesotho that they are not alone.
"Together we can tackle the stigma surrounding HIV and give the young people carrying it the treatment that they deserve -- the childhood so many of us take for granted."