From afar, it seems there's a lot to envy about entrepreneur Elon Musk's life. He's worth $21.4 billion, according to Forbes, and leads two popular, future-forward tech companies, Tesla and SpaceX.
Glamorous as it may seem, it also comes with a lot of responsibility.
"To be frank. I am a little emotionally exhausted because that was super stressful," Musk said in a press conference with NASA after SpaceX test-launched its Crew Dragon spacecraft on the Falcon 9 rocket at NASA's Kennedy Space Center Saturday.
The launch was one for the record books: "For the first time in history, a commercially-built and operated American crew spacecraft and rocket, which launched from American soil, is on its way to the International Space Station," said a NASA press release.
Musk's journey so far has been hard and long: "It's been 17 years to get to this point, from 2002 to now, and an incredible amount of hard work and sacrifice from a lot of people that have gotten to this point," he said at the press conference, acknowledging "a very strong note of appreciation for the SpaceX team."
The SpaceX spacecraft orbited Earth 18 times and then at 5:51 a.m. EST Sunday, 250 miles over the Pacific Ocean to the North of New Zealand, the spacecraft successfully attached to the International Space Station (ISS), a blog post from NASA reported Sunday. The SpaceX space vehicle will deliver more than 400 pounds of equipment and supplies to the space station and will stay connected to ISS for five days, according to a NASA post.
The thus-far-successful unmanned test launch was a milestone for SpaceX, because the Crew Dragon is the spacecraft it will use to send humans to space for the first time. It is also significant for the advancement of the American space program, which retired its only space shuttle in 2011 and has never put people in space via a commercial spacecraft.
Musk is often candid about the emotional toll being the boss at innovative companies like SpaceX and Tesla takes on him.
Last year, he talked about the stress caused by ramping up Tesla's Model 3 production. "You're gonna go a little bonkers if you work 120 hours a week," Musk told Recode's Kara Swisher in an interview in October.
"There were times when, some weeks ... I haven't counted exactly, but I would just sort of sleep for a few hours, work, sleep for a few hours, work, seven days a week. Some of those days must have been 120 hours or something nutty."
In August, he told the New York Times the previous year had been "the most difficult and painful year of my career… It was excruciating."
In 2017, after a Twitter user commented that Musk's social media "shows an amazing life," Musk tweeted, "The reality is great highs, terrible lows and unrelenting stress. Don't think people want to hear about the last two."
A tweet on Sunday seemed to show the billionaire is taking it at least a little easy though; he said he was eating toast and jam while listening to Bob Marley.
Having toast & jam in kitchen while playing Jamming by Bob Marley
See also:
Elon Musk: 'Paper money is going away'
Elon Musk: Moving to Mars will cost less than $500,000, 'maybe even below $100,000'
Like this story? Subscribe to CNBC Make It on YouTube!