More than 30 percent of American workers today are part of the Millennial generation, making them the largest shareholder of the American work force, above both Gen-X and Baby Boomers. With Millennials practically owning the labor force these days (and into the future), business leaders are constantly looking for new ways to attract and retain these rising professionals. The answer, it seems, boils down to one key factor: flexibility.

Studies show flexibility is one of the most important factors Millennials use to evaluate a job opportunity. While flexibility at work (whether that be in the form of flexible workspaces, remote work options, or flexible hours) may seem like a productivity hazard, employers can actually benefit greatly from it. For example, 22 percent of Millennials say they would be willing to work more hours and 82 percent would be more loyal to their employers if they had flexible work options.

But where flexibility can really have an impact is on retention: 34 percent have left a job because the employer did not provide flexibility. Clearly flexibility at work is critical to the Millennial way of life -- but why?

Here are three key factors influencing Millennials' preference for flexible work options.

1. Work-Life Balance

The U.S. Bureau of Labor Statistics reports 20 million Americans actively choose to work part time for more flexibility. As for Millennials specifically, Deloitte's 2016 Millennial Survey found 88 percent wish they had the ability to choose when they start and finish work.

This flexibility supports the desire for better work-life balance so they can create schedules that work with their lives, including when and where they want to work.

2. Technology

Millennials have no interest in the traditional 9-to-5 schedule. They prefer to set their own hours and complete tasks in the way that works best for them. This means employers need to offer flexibility that gives them the option to work remotely, attend meetings virtually, and collaborate online rather than in face-to-face meetings.

Millennials thrive on technology that provides this level of flexibility -- from workplace apps that increase mobility to virtual workstations and cloud-based collaboration tools.

3. On-Demand Work

Another factor driving Millennials' need for flexibility is the growing gig economy, or on-demand work options. On-demand jobs are appealing to Millennials because they offer exactly the type of flexibility they desire -- the ability to set their own hours, seamless technology to find and complete work, and the ability to take on work or "gigs" that appeal to them most.

According to insights from Mary Meeker, one-third of Millennials consider themselves freelancers who thrive in the gig economy, and 32 percent say they expect to be working mostly flexible hours through on-demand jobs in the future.

As a business leader, you can use these insights to build flexibility into your company culture and workplace policies. After all, when the largest portion of the work force begins demanding better flexibility, organizations must find a way to comply.