Most people probably envision it as one of the more glamorous, exciting jobs out there, but what's it really like to be a NASA astronaut? If you're planning on making the move to becoming an intergalactic explorer, you might want to make sure that your expectations are in check first. 

Kjell Lindgren, one of NASA's 47 active astronauts today, just returned from spending six months in outer space in December, a childhood dream that he worked toward his entire life.

Lindgren went through an 18-month hiring process with three main requirements: U.S. citizenship, possession of a bachelor's degree in a STEM major and at least three years of related professional experience or 1,000 hours of pilot-in-command time in a jet aircraft.

Despite serving in the Air Force and being a flight surgeon at NASA for two years, Lindgren was still blown away by the level of the other applicants when he was finally accepted for a final in-person interview.

"Meeting the 19 other candidates made me feel like there had been a mistake," he said. "It's very humbling to have been chosen and makes me want to do a good job because any one of those guys could have done just as good a job as me, if not better." 

After two and a half years of general training and two years of mission-specific training, astronauts finally make their way into space. But what then?

Ariel Waldman, author of "What's It Like in Space? Stories from Astronauts Who've Been There," interviewed dozens of international astronauts and suggests a somewhat tame version of what happens in space.

"Going into space is no doubt an epic endeavor, but it often produces these epic stories that we see in media," she said. "The reality, as I discovered in my many conversations and interviews with astronauts, is that it's a lot more relatable than you would think. A lot more human - making mistakes, having awkward moments, trying out silly experiments."

Lindgren echoes these stories, describing the experience as lots of exercise, training and research, and claims that after awhile, it can become surprisingly mundane.

"The novelty of floating faded so quickly," he said. "I describe it as one of my greatest disappointments of flying in space."

After the first three or four days in space, Lindgren said that his brain adjusted to floating and it felt normal.

"I got better at it, and it was still amazingly fun to float around, but I was disappointed that my brain had accepted that it was normal," he said.

With NASA planning on getting humans to Mars by the 2030s, there will be no shortage of people looking to live out their space exploration dreams. However, if you're in this boat, you might want tot make sure that you know what it's really like to be a NASA astronaut so you're not let down by the experience.