As the world of business becomes increasingly disruptive, there are few things startups and small businesses can still rely on. Gone are the days when superior tactics won the day. And savvy strategy? It's not enough.

Today your best advantage is your company culture -- one where creative, inquisitive thinking is built in at every level and nurtured in every person; a culture that's adaptable; and most important, one that's not just aspirational.

A company's culture doesn't happen overnight. And it's difficult to imbue it in every single person and everything your organization does. That takes tough love, the kind that encourages others not to simply to follow your lead, but to claim the culture as their own. Even if you do those things well, your risk of failure is still higher than you think. Today, more than ever, leaders must learn to turn the tough love on themselves.

While there are many examples of cultures that work and stand the test of time, few have the resilience and effectiveness of the deeply embedded culture of the U.S. Marine Corps. It isn't just their success in the field, it's the way they carry the culture far beyond active duty. "Once a Marine, always a Marine" is how they shorthand it. Even if what you do has nothing to do with defending the nation, the lessons of culture and the tough love Marines and their leadership pursue is relatable to all business owners.

To gain their insights you must first erase the mythology many of us carry in our heads about military leaders. They're not Jack Nicholson in 'A Few Good Men.' Former Marine Colonel and leadership educator Michael Belcher put it more bluntly. "The cold, calculating, yet extremely capable, leader of folklore doesn't elicit trust." That kind of leader, "merely enforces compliance by eliciting fear." In fact, he says "without a foundation of trust, people in the organization may comply outwardly but they're much less likely to conform privately -- to adopt the values, culture, and mission of the organization in a sincere, lasting way."

And, really, that's what has to happen before anything else. You must define your values, culture, and mission before anyone can follow or lead. The Marine Corps have consciously placed a strong focus on this foundation as the first thing new recruits learn. How they go about it is instructive; what they do after is everything. 

First, recruits learn self-awareness. It's pretty hard to adopt a culture as your own if you lack a sense of who you are and who you want to become. Then, they learn context to get a sense of the place and culture they are about to become a part of, such as its history and customs -- and why they exist.

Connecting the dots comes next. Recruits learn that everything ahead of them has a connection to what they learned before, and that everyone, including the new recruit, plays a vital role in shaping it all. No one is marginal, no matter their rank.

Then, and only then, the focus turns to action. Skills are taught, tested, and honed -- all through the lens of what they learned first. 

But that's not where it ends. The most important step is what happens next: Marine leaders actually hand over the keys. It's not that they resign their commissions; instead they allow new recruits to actively apply the lessons they've learned, by testing and challenging the culture -- and their leaders -- time and time again. They actively invite new views. They honor inquiry and challenges made in the context of the culture and for the good of that culture. In fact, they expect it. It's central to the training of both recruits and their leaders.

The key to turning your startup's culture into a competitive advantage is to always remember that shaping culture is a job never complete. Taking a page from the Marine Corps, make sure your culture is allowed to be questioned, tested, and encouraged to evolve -- bit by bit, by every person in your company, every day, in every situation. It is, in the end, the only way to ensure that it not only survives, but also thrives, and stands the test of time.