The 'Real Steel' actor and his wife Deborra-Lee Furness were devastated when they were told they couldn't have kids naturally but now they know it was fate to welcome Oscar, 11, and six-year-old Ava into their lives.
He told Australia's Herald Sun newspaper: "It was painful. It's not easy. You put a lot of time and effort into it, so it's emotional. I think any parent can relate - trying to have children is wonderful and when you feel as though that's not going to happen, there's a certain anxiety that goes with it.
"We thought we'd have a kid or two biologically and then adopt. But when we decided we'd had enough of IVF, we went ahead with adoption.
"From the moment we started the adoption process, all the anxiety went away. I don't think of them as adopted - they're our children. Deb and I are believers in I suppose you could call it destiny. We feel things happened the way they are meant to. Obviously, biologically wasn't the way we were meant to have children."
Although he admits family life isn't always easy, he knows he and Deborra made the right choices.
He said: "Now, as we go through life together, sure there are challenges, but everyone's in the right place with the right people. It sounds airy-fairy, but it's something we feel very deeply."