Sir Elton John thinks about his son "24 hours a day".

The British singer and his partner David Furnish are proud parents to 18-month-old Zachary. Elton, 65, is famed for his lavish lifestyle choices and wealth of A-list friends, but says Zachary has transformed his way of thinking.

"I think it changes everybody. It's the most wonderful thing that you could possibly go through. I regret a little bit that I didn't do it sooner, but life happens for a reason the way it happens," he mused in an interview with UK TV show Daybreak.

"He's changed our lives. Everything is about him now. Everything in the house has got to be child-friendly and child-proof. It's about what's best for Zachary and not what's best for David and myself.

"I thought it was going to be more difficult than it was. I was fairly set in my ways before I became a dad, but the first moment he appeared on Earth, that love you have. You think about him 24 hours a day."

Elton has battled drug and alcohol addictions in the past. The star says his more difficult years shaped him as a person.

"I'm glad I lived my rock star years because it makes me appreciate now what I shouldn't be doing. When I was younger I did everything I possibly could and had a great time. I took it too far and I didn't know when to stop," he admitted.

"The good thing about it is life since 1990 has been all about trying to grow up, trying to see things from a different perspective, listening, and having a great time."