British singer Sarah Brightman initially turned down the opportunity to travel into space because she didn't feel ready for the challenge.
The classical singer, who was once married to theatre impresario Andrew Lloyd Webber, is set to visit the International Space Station in 2015, but the star reveals she almost missed her chance.
She tells Britain's Seven magazine, "When I first was asked to do it, I thought 'I don't think so'. It's a really important step to take. But the second time I felt ready.
"I'm feeling anticipation about the flight, but no apprehension, just how I feel before I go on stage."
Brightman has undergone tests to ensure she is fit enough for the mission, and she reveals medics are impressed with her abilities.
She adds, "The doctor, who's worked with a lot of the astronauts who've been up for years, was saying... 'I don't believe this. Even on the brain scans you're coming out perfect.'"
The singer has also embarked on a training program, and is enjoying the challenges in a simulator.
She explains, "It was full on. I didn't know what to expect but it was far more than I expected. But I'd already sort of been trained for it by all my years of touring, in terms of the uncomfortableness, not knowing what to expect, having to create something out of nothing.
"Doing the centrifuge (gravity and acceleration test), I was completely calm, my heart rate hardly went out at all, I didn't have a problem with it. I didn't know how I'd deal with the claustrophobia either being shut into the air compression chamber, but I felt most relaxed, almost sleepy in those confined areas."