Olivia Newton-John suffers from acrophobia.
The 66-year-old actress has had an irrational fear of heights for as long as she can remember which has affected her life.
In a feature for the new issue of Us Weekly magazine entitled '25 Things You Don't Know About Me', Olivia revealed: ''I'm terrified of heights.''
Despite her phobia, the 'Grease' star won't let the condition affect her life and she still flies and travels to vertically challenging locations.
She added: ''I have walked more than 120 miles on the Great Wall of China and I have to spend at least an hour ever day outside.''
Even though she is scared of heights, Olivia even married her husband John Easterling - the president of the Amazon Herb Company - on top of a mountain in a private Incan spiritual ceremony in Cuzco, Peru.
She said: ''I married 'Amazon John' Easterling on a mountaintop in Peru.''
Olivia and John tied the knot in June 2008 and after seven years being wed, the blonde beauty knows how to keep him happy - she makes him a delicious breakfast every morning.
She shared: ''I collect fresh eggs daily to make breakfast for him.''