Hollywood star Will Smith has admitted he dissolved into tears as he watched his teenage daughter Willow drive away from their house for the first time.
Will, who is also father to sons Jaden and Trey, confessed he is more of a soft touch than people think.
Arriving at the European premiere of his new film Collateral Beauty, in which he plays a grieving father, he said: "I cry a lot. My daughter just turned 16 and I watched her drive away from our house about three weeks ago.
"I was out there in the driveway as she was driving away just boo-hooing like crazy, thinking 'My baby is 16 years old'.
"That was my highlight of the year too, it felt like a huge parenting accomplishment but she doesn't really pay enough attention, she feels safe in the world so when she's driving she's very happy, I want her to feel less safe when she's driving."
In the film The Men In Black star plays an advertising executive struggling to deal with the loss of his daughter by writing letters to Love, Time and Death.
Will said he tried to avoid thinking about his own children when dealing with the difficult subject matter.
He told the Press Association: "I try not to go method acting where I'm allowing those thoughts of the character's traumas to drift in to my own.
"I try to separate it as much as possible but it was much more watching the film when it started to hit me in that way. I cried my eyes out."
Will's own father was diagnosed with cancer shortly before the film began shooting and died last month but he said making a movie that dealt with death was an important experience.
He said: "I feel like we created something special, if it hits a person at the right time it can be helpful in someone's life.
"It was a beautiful opportunity to get perspective and get clear on the things that are really important, and how much crap we do that just really doesn't matter it's painful but great to be cleansed of some of those material world addictions."
Will stars opposite Dame Helen Mirren, Keira Knightley, Ed Norton and Kate Winslet in the film but Dame Helen said she became convinced she was really sharing the screen with an alien.
She said: "He's a legend and he should be because there is something legendary about him.
"My theory is he's not a human being at all, I think he's an alien but he's an incredible, brilliant advertisement for aliens because they are the kindest, most generous, most loving of all creatures. I've never met anyone like him."
She added she believes films with a message of unity are particularly important at times of division, saying: "This film is very much about finding, in the most simplistic way, the silver lining in the cloud and there have certainly been a lot of clouds in this human life of ours, on this planet in the past year.
"I think it's beholden upon all of us to find the positivity, love and inspiration. We are all connected and we are all ultimately the same creature and that is what we have to remember."
Collateral Beauty will be released in UK cinemas on December 26.