Keith Urban's "heart stretched" the day he became a father.

When asked how life changed when he became a father, he said: "I think, as Nicole has said, it's just the stretching of the heart. It is an indescribable feeling. It was much like the first time Sunday cried, when she came into the world. There are certain things in life you have to experience, otherwise, it's just a vague concept of what it would be like. It's had such a big impact on my life."

The 42-year-old singer has even altered his musical career so he can spend more time with his family.

He added: "I structured the tour so I would do three shows in a row, then take about three or four days off. Now we have Sunday, it is about enjoying the simple pleasures - just being able to say 'Goodnight' to my girls and not be on the phone doing it.

"It's the real normal things like that that have brought such a grounding to my life. It's a wonderful experience."