Sir Richard Branson is training to become an astronaut ahead of a space mission within months.
The billionaire, who is attempting to get his space tourism company Virgin Galactic off the ground, is in a commercial space race with tech entrepreneur Elon Musk and Amazon founder Jeff Bezos.
"We're talking about months not years - so it's close. There are exciting times ahead," Sir Richard told BBC Radio 4's You And Yours, to be broadcast on Monday.
"I'm going for astronaut training, I'm going for fitness training, centrifuge and other training so that my body will hopefully cope well when I go to space."
While Sir Richard believes Mr Musk is "doing fantastically well" in getting cargo into space and building bigger and bigger rockets, the real tussle is between the Virgin boss and Mr Bezos.
"I think we're both (Sir Richard and Mr Bezos) neck and neck as to who will put people into space first.
"Ultimately we have to do it safely. It's more a race with ourselves to make sure we have the craft that are safe to put people up there."
Sir Richard, 67, hopes to be one of those first space tourists.
He said his astronaut training is going well so far, and he's increased his fitness training by playing tennis four times a day.
"Instead of doing one set of tennis every morning and every evening I'm doing two sets. I'm going kiting and biking - doing whatever it takes to make me as fit as possible."
The Virgin founder is also taking part in gruelling centrifuge training which recreates the pressures the human body experiences during space flight.
All astronauts endure G-force training which simulates the experience of take-off and travel through the earth's atmosphere.
"If you're going to really enjoy the experience, the fitter you can be the better," he said.
Earlier this year Virgin Galactic completed a supersonic test flight of its SpaceShipTwo passenger rocket ship.
It was the first return to the air for the company since a crash in the Californian desert in 2014 in which one pilot was killed and another was injured.