Brad and Jennifer were once hailed as Hollywood's 'golden couple' before their separation in 2005

The couple now have three adopted children - six-year-old Maddox, Pax, 3, Zahara, 2, and one biological child, one-year-old Shiloh.

On his instant family, Pitt said: "Listen, I've always embraced extremes, so it doesn't feel odd to me.

"There's a couple weeks of finding your balance, and then it's in stone.

"It (my family) pleases me so much. I get so warm."

Brad and partner Angelina Jolie with their four children, Maddox, Shiloh, Zahara and Pax

Of his adopted children, Maddox, Pax and Zahara, Pitt told Details: "I don't even see in that, anymore, what their lives could have been. I have to intellectually think about that.

"They are a bond, they are a family. And I want to see those bonds and that family grow.

"And that right there, sitting in our kitchen, is how I want to see the world. It's how I want the world to be."

As for turning 40, the man often described as the 'Sexiest Male in the World', admits he has to work harder to maintain his physique.