Betty runs up and down stairs to stay fit

London: Veteran actress Betty White has revealed the secret behind her fit body -- she runs up and down the stairs of her two-storey house.

"I have a two-storey house and a bad memory, so I`m up and down those stairs all the time. That`s my exercise," quoted the 88-year-old as saying.

"The Proposal" star also said that she eats fries every night (along with a salad or vegetable) and has a hot dog named after her at the Pink`s Hot Dogs in Los Angeles.

"It`s called ‘Betty ‘Naked in the City’ Hot Dog`…because I don`t put anything on it," she said.