International Women's Day has been a celebrated international holiday for decades but it's just starting to generate momentum in the United States, where only 5 percent of large companies are run by women.

You know what that means? They've had to possess almost super-human levels of performance to get to where they are - which makes them worth listening to.

Here are some of my favorite tips from highly-successful, established women from across the spectrum, that can help anyone become a better leader.

Ginni Rometty, Chair, President, and CEO of IBM

During Fortune's 2014 Most Powerful Women's Summit, Ginni said, "I ask myself every day: Did I make decisions and do things that only I could do? If other people can make them, it's not the best use of your time."

Mastering your to-do list is one of the best ways to maximize productivity. This quote is one of the golden rules when setting my daily agenda.

A task should only be on your to-do list if you are the person most qualified to accomplish it. Before placing something on your list, consider if it's better delegated to someone on your team, or if it should be someone else's responsibility entirely.

Use your time and your colleagues' skillsets wisely. It's one of the best ways to get and stay productive.

Judith McKenna, COO of Walmart

When she was a panelist at the 2016 Milken Institute Global Conference, Judith McKenna said, "Never be afraid to recruit people brighter than you are, and never be afraid to recruit people who are different than you. That is sometimes hard to do, but incredibly powerful if you want to create a team that is really effective."

Judith is 100 percent correct - just as you're the best person to run your business, your hires are the best people to run their respective domains. And when there's a healthy difference of opinion and background within the company, you can always be confident that any decision was the right one.

At my company, we trust every team lead to be the "entrepreneur" of their own domain and encourage them to run their department as its own small business. Diversity also plays a big role in our process: Arkadium employees hail from more than a dozen different countries and our New York management team is comprised mostly of women.

The first step to hiring the best is to put your ego aside. If a candidate challenges a preexisting notion you may have, keep your mind open - they might just be the person for the job.

Candy Crowley, former chief political correspondent at CNN

"Whatever you do, be so good they can't ignore you," said Candy Crowley during a 2012 radio interview while discussing her commencement speech at Maharishi University of Management's graduation ceremony.

Indeed, this is the single best piece of advice I can give to young employees looking to stand out: make yourself invaluable.

This requires several steps that are unique to every company and role, but almost always include these key ingredients: working smarter and harder than your peers, for sure, but also a little self-promotion.

Especially in larger companies, the only way some colleagues will learn about your accomplishments is if you tell them. Of course, there's a difference between self-promotion and diminishing the efforts of others. But becoming indispensable is the product of great work and widespread awareness.

At Arkadium, we dedicate two minutes at the end of our weekly company meeting for all employees to call out their "little wins" from the last week - which could be anything from a successful meeting to closing a new deal.

Wendy Clark, CEO of DDB Worldwide

In a 2013 Fast Company interview, Wendy said, "The thing people want most is your focus and attention. You destroy that when you think you're multitasking, because you're not accomplishing either."

There was a time when being able to "multitask" was one of the most sought-after traits. As Wendy so powerfully argues, those days are over.

If you're "multitasking," you're not giving enough attention to anything you're trying to accomplish - especially in today's world, where everything with a screen is constantly calling for your attention.

As the CEO of a company that specializes in creating engaging digital products, I know firsthand how enticing it is. But even if it means turning your phone off, or closing all your windows and tabs and starting fresh, focusing solely on the task at hand is the only way you'll truly accomplish it.