Robin Williams' Son, Zak Williams, Reflects on Seeing His Dad Help Strangers on the Street: 'What Kindness Was All About' (Exclusive)

"It was deeply important to him to help improve the human condition," Zak tells PEOPLE of his dad, who died in 2014 at age 63

Zak Williams is remembering his father Robin Williams' kind and caring spirit.

While speaking exclusively with PEOPLE at the 12th Annual Bring Change to Mind Revels & Revelations gala, the late actor and comedian's elder son opened up about Robin's love of helping people in need, including strangers he encountered on the street.

"When I was a little kid and we'd be walking in San Francisco where I grew up, he would stop, talk to someone on the street — a homeless person — say, 'Hey boss, what can I do for you?' " he recalls. "And we'd see him get meals, food, money."

Related: Robin Williams' 3 Kids: All About Zak, Zelda and Cody

Zak, 41, says his father's display of compassion was moving and inspiring. "He cared deeply about people in need, and I think for me, he opened my eyes to really what kindness was all about," he explained.

Since Robin's death at age 63 in 2014, Zak — along with his siblings Zelda, 35, and Cody, 33 — have made it their mission to carry on their dad's legacy of philanthropy. "It was deeply important to him to help improve the human condition, and that extends beyond helping people laugh and learn about themselves," he tells PEOPLE.

"It also related to how he could actually support organizations materially by helping raise funds and awareness for organizations like the Challenged Athletes Foundation, the [Christopher & Dana Reeve] Foundation and St. Jude's, among many others," continues Zak, whom Robin welcomed with first wife Valerie Velardi in 1983.

The siblings are proud to carry on the "extremely important" work that meant so much to the Good Will Hunting star.

"We see it as a natural extension of what he would want, which is helping bring healing and helping develop resilience for folks, especially young people. He loved kids," Zak tells PEOPLE. "And as a family, we feel it's a natural way to honor his legacy."

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Zak — who is chairman of Glenn Close's nonprofit Bring Change to Mind, which works to end the stigma and discrimination surrounding mental illness — also continues to honor Robin with touching tributes on social media. Back in August, he shared a smiling photo on Instagram of the actor from his Mork & Mindy days to mark the 10th anniversary of his death.

"Dad, it’s hard to believe it’s been 10 years," Zak wrote in the post's caption. "Today, I’m reflecting on the immense love you shared with all of us — your family, your friends and everyone you met."

He continued, "You continue to inspire me every single day to do whatever I can to help create a more connected and loving world for our family. Love you forever. ❤️."

Related: Robin Williams' Daughter Zelda Shares Family Traditions: 'We Would Eat Together Every Tuesday' (Exclusive)

On what would have been Robin's 73rd birthday on July 21, Zak shared a post on X (formerly Twitter) reflecting on how his dad touched so many people's lives.

"I remember you for all the hope and joy you brought to the world," he wrote. “There's not a week that goes by without someone sharing with me how you helped them through a dark time or a rough patch. I'm so grateful to be your son. Love you forever.”