This is what it takes for a woman to succeed.

In a bid to understand what makes female chief execs tick, executive recruiters Korn Ferry interviewed and studied the careers of 57 women who lead some of America’s most prominent companies. The women weren’t identified in the firm’s report, first published in the Harvard Business Review, but the headhunters say they include 41 females who helm Fortune 1000 companies. The findings aren’t always pretty, but provide some insight into a small but growing number of women head honchos.

One unsurprising, if upsetting, conclusion was how much leadership potential Corporate America is throwing away. According to Korn Ferry’s investigation, women CEOs tend to have worked harder and longer at roles lower down the totem pole before they got the chance to head companies. These women were, on average, four years older than comparable males when they took power and had worked in a more diverse range of fields.

This might make for inspirational hashtag slogans, but some of the women weren’t happy at having to prove themselves for longer periods. In addition, by spending more time in arguably less important positions, women had less time to lead when they eventually took over. “With women apparently expending more energy to achieve the same result, the longer runway gives them fewer years to have an impact in the top job,” Korn Ferry concluded.

The findings also confirm some other stereotypes that apply to female leadership. Korn Ferry scored leaders according to a “benchmark for humility” and found that women were less likely to self-promote and quicker to express appreciation to their colleagues. On one hand, this suggests lower confidence levels on the part of female bigwigs. Indeed, two-thirds of the women surveyed said they didn’t realize they could be chief execs until someone told them.

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But there’s also a flipside to the lack of swagger. “When you have that kind of humility people want to help you, and it’s a strength to ask for help, not a weakness,” one of the CEOs told Korn Ferry. In turn, this can translate into a more collaborative atmosphere at companies led by women.

The report also provides tips for corporate boards and recruiters facilitate women—who currently lead only 32 of the Fortune 500 companies—ascending to the top. Many of them are well-hashed: established systems of mentorship and show more women that there’s a path to become CEO, for example.

Korn Ferry also warns that firms should be careful not just to promote women during crisis moments, a not-unusual scenario it terms a “glass cliff.” For instance, Hewlett Packard Enterprises chief Meg Whitman took over a larger company—that she subsequently divided—after her predecessor had overseen a 46% decline in its share price.

Whitman’s still around, but “often…such a high-profile failure can tarnish, even end, a career,” the recruiters writes.” Organizations need to provide opportunities for women to regain their footing if a high-risk situation fails, or else they risk losing precious talent.”