A happy marriage is the key to Olivia Newton-John's radiant good looks.

The blond actress unveiled her Madame Tussauds figure in Las Vegas on Saturday [09.08.14] - in which she appears as Sandy, the iconic teenage girl she played in 'Grease' - and Newton-John claims that her marriage to John Easterling, 61, is the reason her beauty remains intact.

Asked how she has managed to retain her youthful looks, Newton-John - who was John Travolta's love interest in the flick - said: ''Facial surgery? I haven't done any of that. I guess I'm lucky. Genetically, I'm like my mum and she looked great right up until her death in 1989. But I think the real secret is that I'm very, very happy.

''I have a wonderful new husband and we're very compatible.''

Newton-John - who married her husband in 2008 - also revealed she abides by a fitness regime that ensures she looks and feels healthy.

She said: ''I play tennis and go to the gym three or four times a week, too. I feel great and certainly don't worry about age - it's just a number.''