Millions of people have successfully run a marathon, but how many can say they've run one in space?

The London Marathon is set to take place on April 24, 2016 with over 37,000 participants, but British astronaut Tim Peake won't be there. He'll bit in Earth's orbit onboard the International Space Station. Rather than run the marathon in 2017, when he's back on Earth, Peake decided to run it from space to raise awareness for the Prince's Trust charity.

"As soon as I got assigned to my mission to the International Space Station, I thought wouldn't it be great to run," said Peake in a statement and video released by the Prince's Trust. "The London Marathon is a worldwide event, let's take it out of this world."

And thanks to virtual reality, Peake says he'll feel like he's actually there.

"The thing Iím most looking forward to is that I can still interact with everybody down on Earth," said Peake. "Iíll be running it with the iPad and watching myself running through the streets of London whilst orbiting the Earth at 400km above the surface and going 27,000km per hour."

Of course in microgravity, Peake wouldn't be able to run without a harness holding him down. Unfortunately, the shoulder straps and waist belt can cause quite a bit of discomfort after 40 minutes according to Peake. Because of this, he doesn't think he'll be setting any personal bests, but hopes to complete the race in under 4 hours.

This isn't the first time Peake will run the London Marathon, he did so back in 1999, clocking in at 3:18.50. His six-month mission to the ISS is set to begin on December 15.

The feat of running a marathon in space has actually been accomplished before. NASA astronaut Sunita Williams ran the Boston Marathon from the ISS on a treadmill in 2007.