Cindy Crawford says the secret to beauty is being happy.

The 49-year-old supermodel and businesswoman thinks ''smile lines'' are the best wrinkles to have and, although she's like any other woman who wants to discover the perfect beauty product, she thinks looking great in the moment is all about your mood.

She said: ''The biggest secret really is just being happy, because that shows on your face more than anything. If you're going to have lines, you might as well have smile lines.''

However, a smile goes well with a decent sunscreen.

She said: ''What I've learned from taking care of my skin for over 20 years now is that it adds up. At 50 you're going to be like, 'Wow, I'm so glad that I started using sunscreen or a good eye cream.' I don't smoke and I drink a lot of water, so I'm pretty healthy.''

But the brunette beauty - who rose to fame on the catwalk and in fashion magazines in the late 1980s and throughout the 90s - insisted that women shouldn't rely too heavily on expensive beauty products.

She told ''We all want that one product to put on. It's like the perfect pair of jeans - you're looking and looking for it, but it never happens. I think sometimes women expect too much (from a product), like having overnight success.''