"I never really dealt with what had happened," he says in a new documentary

Prince Harry was only 12 years old when he tragically lost his mother Princess Diana in a Paris car accident, and he’s continuing to open up in new ways about his grief.

In a documentary for ITV focused on his charity work in Lesotho, Africa, the 32-year-old royal admits that he spent a long time suppressing his feelings about his mother’s death.

“I never really dealt with what had happened. It was a lot of buried emotion,” Harry said. “For a huge part of my life I didn’t really want to think about it.”

He continued, “I now view life very differently from what it used to be. I used to bury my head in the sand, and let everything around you tear you to pieces.”

Prince Harry has found meaning — and a way to carry on his mother’s legacy — in his charity work, including Sentebale, the charity he co-founded with Prince Seeiso of Lesotho in 2006 to improve conditions for those affected by HIV and AIDS in the country. In May he spoke with PEOPLE about his ongoing charity work, saying, “all I want to do is make my mother incredibly proud.”

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Princess Diana made strides at a time when stigma surrounding HIV and AIDS left many uninformed people afraid to touch those with the illnesses, famously shaking hands with patients without gloves on.

“I need to make something of my life… I was fighting the system, going, ‘I don’t want to be this person,’ ” Harry explained of the difficult years following Diana’s death. “My mother died when I was very, very young and I don’t want to be in the position. Now I’m so energized, fired up, to be lucky enough to be in a position to make a difference.”

Harry first traveled to Africa during his gap year in 2004.

“What started as an idea of me turning round and saying, right, I’ve got a year off, I want to do something really constructive with my life, want to do something that makes my mother proud,” he shared. “Someone said, right, go to Lesotho, it’s like where the hell is that? Now I can see exactly where I want to take it. I have huge amounts of passion for the causes and interests and charities I’m involved with.”