Matt Damon admitted his fears for his young daughters growing up in an era of social media, as he promoted his new film Jason Bourne.
Matt reprises his role as the eponymous former CIA assassin, now in a "post-Snowden world" where the line between protecting personal privacy and state security is regularly crossed, particularly in the case of social media.
The father-of-four confessed he was a "dinosaur" who avoided sites like Twitter and Instagram but said he was glad they were not around to capture the indiscretions of his youth, unlike for step-daughter Alexia, 17, and daughters Isabella, 10, Gia, seven, and Stella, five.
He said: "I do worry about my daughters on social media.
"We talk about it, and I'm not on these things, I'm kind of a dinosaur, but it's scary to think that some kind of teenage mistake - something I could have done, and millions upon millions of people do foolish things as teenagers - could somehow follow someone around forever. That's a really scary thing.
"Kids are supposed to be making mistakes in adolescence, that's what it's for, make those mistakes in the safety of your adolescence and bring a little more wisdom into adulthood, but I definitely worry about it."
Being well into adulthood had one big disadvantage for Matt when filming.
The 45-year-old admitted he struggled a lot more with the stunts required for his fourth film in the franchise, having started on the Bourne Identity when he was 29.
He said: "They were much much harder, everything was harder.
"Just getting into shape was an up-at-dawn-siege everyday and the diet, that was the hardest part.
"It was a very strict diet because I like to eat, so that was tough."
Jason Bourne is in UK cinemas from July 27.