"A large part of what we're doing through this grieving process is giving and spending time focusing on others", he continued.
Zak Williams, William Reeve, Alexandra Reeve Givens, Matthew Reeve
"It's tremendously sad ... we're trying to stay strong. The key thing that I want [people] to know is that we're doing okay," he added, after speaking to Entertainment Tonight and People.
When asked how Robin's fans had helped, he added: "People shared their really loving words and supportive words, art, and all sorts of amazing tributes to my father."
The Christopher And Dana Reeve Foundation A Magical Evening gala, also included a speech by Zak. The annual event raises money for research into spinal cord injuries, and was held in New York.
Late in October, Zak, along with his younger siblings, Zelda and Cody Williams, took a moment to honour their dad ahead of a baseball game in San Francisco, which saw Robin's team the San Francisco Giants play against the Kansas City Royals.
Zak Williams gives his speech at the The Christopher And Dana Reeve Foundation A Magical Evening gala
Taking to the AT&T Park mound, Zak – the eldest of the siblings – threw the ceremonial first pitch to actor Billy Crystal, who caught the ball in his glove, leaving the stadium to erupt in joy.
Following Robin's death on 11 August, tributes flooded in from fellow Hollywood stars and the actor's family and friends.
Zelda Williams, Cody Williams and Zak Williams paid tribute to their late dad Robin
The Mrs. Doubtfire star was remembered in a private funeral, but also in the public sphere, with Billy commemorating his friend at this year's Emmy Awards. Robin was remembered in the "In Memoriam" segment, which commemorates late actors who have contributed greatly to television.
Billy, who spoke about the love and impact Robin had on his fans, was the "perfect choice" for the speech, said Emmy producer Don Mischer.