The late actor Robin Williams died in 2014 at the age of 63. His children took a heartfelt moment to remember their loving father and think about what he left behind.

On what would have been his 72nd birthday, Robin’s daughter Zelda Williams and son Zak Williams paid respect to him on social media.

His daughter wrote about him on Twitter to honor him.

She posted a picture of her late father on the picket line in New York during the strike in 2007. In the picture, Robert was standing with other protesters who were carrying signs that said “SAG WGA ON STRIKE.”

She wrote, “Happy birthday to Poppo, who definitely would’ve been out there fighting the good fight for art and artists today and always.”

People magazine says that Zak posted a picture of his father from the past on his Instagram page. In the shot, his father was wearing headphones and smiling at the camera.

He wrote, “Happy 72nd Dad! Was remembering how much I used to love that look you’d give. That look with a mischievous, loving grin that your friends and loved ones knew so well. Joyous and curious and wondrous. Miss you and love you forever!”

Robin was in the movie Jumanji and spoke out for the rights of artists.