In this next installment of my series on what constitutes the American Dream, I want to focus on one of its most important features: constantly pushing the frontier of whatever it is you’re trying to do.

One of my favorite places to go and take visitors to in the DC area is the Dulles Air and Space Museum. It’s a museum filled with marvels of achievements and aspiration. You can find the Discovery Shuttle there that led 133 space missions. You can find the Enola Gay, which represented a bleak episode in human history of dropping the first atomic bomb. You can find a Concorde that pushed the frontier of supersonic commercial flights in its heyday. And you can find the SR-71 Blackbird that is also iconic as one of the fastest planes ever built and flown.

But for me, the most inspirational part of the museum—and the first spot I head to when I enter—is the Red Bull Stratos capsule. Thirteen years ago, Austrian skydiver Felix Baumgartner became the first person to break the sound barrier, the highest skydive, and the highest vertical exit. Baumgartner literally went to the frontier of space and jumped. With the support of Red Bull, an Austrian company that needs no introduction, and a team of various individuals and companies involved in the process, a truly monumental human endeavor was accomplished. Baumgartner trained for five years to achieve what people thought was impossible—or at least spectacularly difficult. It made for one of the best Red Bull commercials of all time, but it also provided scientists with a lot of information about many different aspects of space flight, jumps, and the body’s reaction to different pressure points.

During the training, there were numerous close calls that could have led to mission failure, bureaucratic processes that almost stopped the project, and so many different pieces of the puzzle that needed to work at the same time that its accomplishment was truly an amazing feat of human creativity and persistence. It was an American Dream of one person that ended up including many other people. This is a special aspect of the American Dream: while people are certainly responsible for setting and living their own American Dreams, there is almost always someone else who helps us get there. In this case it was a huge team of experts and companies. But in other cases, it could be a parent, a schoolteacher, a partner, etc.

There were so many people involved that it’s tough to discuss each part of the team and the process, but here is an amazing two-hour documentary about the feat that I highly recommend. For me it represents the pinnacle of having a dream, working hard to pursue it, and living it out—and in a way that is so visible and inspirational for others to see that I think it certainly elevates what it means to push the frontier, in this case quite literally.

Another amazing example of the American Dream in that museum, and my second-favorite exhibit, is one of FedEx’s first planes, named Wendy after FedEx founder Fred Smith’s first daughter. Smith founded FedEx after working on the idea for an undergraduate term paper at Yale. He revolutionized reliable overnight delivery in a “computerized information age” as he called it. After serving in the military, he founded and fundraised to start the company and committed to his vision, overcoming many obstacles—even risking a fuel bill at a blackjack table in Las Vegas. It seems like founding the company and building it throughout his life was his American Dream, and it certainly pushed the frontier of the logistics industry worldwide.

But let’s step back a bit. The American Dream is about having a vision, pursuing it, and constantly pushing the frontier of what people think is possible—if you are dreaming the biggest of dreams. Historically, pushing the frontier was about expanding the geographical frontier of the United States. European settlers pushed the frontier in their own lives by coming to the United States in search of a better future. Once they settled here, pushing the frontier meant expanding their reach within the United States, both within the original territories they were part of it and later expanding further west as was depicted in John Gast’s 1872 painting, American Progress.

Even as the geographic frontier was being settled, Americans sought to push the frontier in other fronts and industries.

There are many innovations in oil and gas from the advent of industry, which even helped save the lives of whales to some degree, as it had been whale oil often used to fuel lamps. More recently advances in fracking have allowed the oil energy industry to push even further and develop more. The electrical wars between Nikola Tesla, Thomas Edison, and George Westinghouse pushed the frontier of advances in electricity production and distribution.

Leaders like Walt Disney pushed the frontier in animation. Sam Walton pushed the frontiers of retail and discount stores to build an empire. Certainly, Elon Musk is now pushing frontiers in a variety of industries and companies. And there are other modern examples from various companies that are pushing the frontiers in their respective industries, like Anduril and Palantir in the defense industry.

One of my favorite examples is a magnificent team pushing the frontier of ocean cleanup, led by (in my opinion, American Dreamer) Boyan Slat. Though he wasn’t born in America, he received a Thiel Fellowship to start working on his project.

Pushing the frontier in movie production has certainly been a key aspect of the history of Hollywood, and one of the best representatives of that nowadays must be Tom Cruise with the lengths he goes to push the frontier in his own acting and stunts for the Mission Impossible franchise.

More recently another favorite example has become Michael Milken, whom I recently met at the Milken Global Conference. Milken pioneered and pushed the frontiers of financial innovation, leading what he calls the “democratization of finance.” Milken has also led the creation and soon-to-be inauguration of the Milken Center for Advancing the American Dream, which will showcase how so many Americans have pushed the frontiers in their own lives and crafts by living their dreams.

But it is certainly not only in business that America has excelled. Americans have pushed the frontier in many other areas including civil rights, sports, healthcare, etc. In many cases an American Dream doesn’t need to be grandiose; it could simply be what you’re looking for in terms of having a good family life and a fulfilling career. You might decide to push the frontier of what you think is possible in order to achieve it. You might wake up at 5 am to start work earlier to have more time to spend with your family during the day, when you thought you couldn’t wake up that early and be productive. You might spend the effort to figure out ways to have a better work-life balance to give yourself time to spend with the family.

Or as a completely different example you might push the frontier in terms of solving impossible problems like the Vesuvius Challenge, which consisted of deciphering scrolls buried after the explosion of Mount Vesuvius, a challenge started by American entrepreneurs and won by a team of three students, one of which was American as well.

It is difficult to just name a few possibilities for frontier-pushing, but that is exactly why the United States and the culture of the American entrepreneurial spirit is so special. And in that sense, it is also why the American Dream is so special. The pursuit of excellence and pushing the frontier of what others think is impossible is an important path to fulfill one’s human potential and achieve the American Dream.