Sarah Robb O'Hagan is the president of Equinox Holdings, Inc., one of the biggest players in the $30 billion fitness industry. (In 2014, the international chain brought in a reported $822 million in revenues, up from the previous year's $740 million.) She's held senior positions at corporate giants, including Gatorade, Nike, and Atari Interactive.

In her current position, where Robb O'Hagan oversees multiple teams of diverse age groups, she finds one career trend to be hugely concerning: the rate at which Millennial employees tend to hop jobs.

"The one thing I worry about for Millennials is that they don't quite stay long enough to really get the experience before hopping to the next thing," she told an audience during a panel discussion earlier this month in New York City.

Her advice to young workers: "Just make sure you really understand this part of this company that you're in before you move to the next one."

Robb O'Hagan spoke in conversation with a trio of women at the top of their fields (Daniella Yacobovsky, co-founder and CEO of BaubleBar, Norma Kamali, fashion designer and CEO of The Wellness Café, and Erica Hill, co-anchor for NBC's Weekend Today). The event, called "Women Helping Women," was hosted by Dress for Success, a not-for-profit organization that helps women get started in their careers, by providing suits, as well as support and mentorship.

Robb O'Hagan is correct in noting that Millennials hop jobs at an unusually rapid pace, a growing body of research suggests. Nearly half of Millennials (43 percent) planned to actively look for a new job at the beginning of 2015, according to a February report from the New York consulting firm Aon Hewitt. What's more, a 2013 study by Millennial Branding and, a career networking site, found that as many as 30 percent of companies lose 15 percent or more of their young hires each year. 

This Millennial wanderlust may have something to do with their relative optimism; according to 2014 Pew Research data, 49 percent of Millennials are bullish on the future of the U.S. economy, and agree that the nation's best years are still to come.

Still, hopping jobs may not be the best thing for one's career, as Inc. columnist Lou Adler writes. For one thing, it can make the employee appear unstable, and uncommitted to bigger corporate goals.

On the other hand, some experts argue that hopping jobs can actually be a good thing -- provided the employee is leaving for the right reasons. "Millennials are all about temptations that they can do better," noted Dan Schwabel, the founder of Millennial Branding, in a recent interview with CNBC. "You can't make a short-term hop if you don't know your long-term goal," he said.

Robb O'Hagan adds that she certainly needs her Millennial workers; the best companies, after all, are the ones that foster innovation among younger and older teams.

"A couple of times, like at Gatorade, I was there to turn the business around because they had lost so many people that were there in the beginning," she said. "Brands are like families. You do need the history and the heritage, and I also think you need the new Millennials and all that good stuff. They both need to come together."