Cameron Douglas says late grandfather Kirk is a "hard" act to follow

Speaking to the Hollywood Reporter, he said: "Losing him is one of those things that, even when you sort of see it coming -- he was 103 -- it's still difficult.

"I take solace in the pride of being his grandson and having had the opportunity to spend as much time with him as I have.

"When I look at his life, what he accomplished and the way he carried himself, it's hard for me to imagine anyone doing it any better."

The 'Runner' star revealed Kirk never really tried to pass on a partcular "secret" about his craft, but instead focused on teaching his grandson more valuable lessons.

He explained: "He always used to tell me -- even before I got this job when I was doing a lot of auditioning -- how he thought that I was truly talented and to keep going.

"To hear that coming from him was enough. He didn't really have a secret about acting to pass along to me.

"His secret was hard work, being prepared and showing up. Then, if you have the talent and the work ethic, it will work out. That's what's ingrained in me from him."

Meanwhile, Michael confirmed his father's death last week, as he expressed his "sadness" at the news in a lengthy statement.

He said: "It is with tremendous sadness that my brothers and I announce that Kirk Douglas left us today at the age of 103.

"To the world, he was a legend, an actor from the golden age of movies who lived well into his golden years, a humanitarian whose commitment to justice and the causes he believed in set a standard for all of us to aspire to.

"But to me and my brothers Joel and Peter he was simply Dad, to Catherine, a wonderful father-in-law, to his grandchildren and great grandchild their loving grandfather, and to his wife Anne, a wonderful husband.

"Kirk's life was well lived, and he leaves a legacy in film that will endure for generations to come, and a history as a renowned philanthropist who worked to aid the public and bring peace to the planet.

"Let me end with the words I told him on his last birthday and which will always remain true. Dad- I love you so much and I am so proud to be your son."