WATCH: This is what facing 9G force looks like
It doesn't look pleasant at all, but this is the challenge wannabe astronauts and pilots must face.
Centrifuge training involves facing huge G-forces, which can cause blood to rush to the brain causing unconsciousness.
Pilots and astronauts must train their body against this in order to do their job.
In this video, which was uploaded to YouTube yesterday, a man shows us just how uncomfortable the training can be.
The video is on its way to going viral, as it has already been viewed more than 140,000 times.
Off screen, a man can be heard advising the brave trainee what to do to withstand the pressure.
"Squeeze the butt, squeeze the legs, breathe..."