International Women's Day: 21 female stars' best life and career advice

March 8 marks International Women's Day -- an occasion to recognize women's achievements in different industries and around the world.

According to the United Nations' website, the first National Woman's Day was observed in the United States on Feb. 28, 1909, and the UN began celebrating International Women's Day on March 8, 1975 during International Women's Year.

To mark this year's International Women's Day, ABC News compiled a list of the best life and career advice from some of the biggest stars today. Their words of wisdom are below.

Oprah “The highest honor on Earth that you will ever have is the honor of being yourself,” Winfrey said on “Good Morning America" on March 7. “Your only job in the world, people think your job is to get up and go and raise money and take care of your families and stuff, that’s an obligation that you have but your only true job as a human being is to discover why you came, why you are here.”

Meghan Markle"I hear a lot of people speaking about girls' empowerment and women's empowerment. You will hear people saying they are helping women find their voices," Markle said at a forum for The Royal Foundation last month.

"I fundamentally disagree with that because women don't need to find their voices. They need to be empowered to use [their voices] and people need to be urged to listen," she added. "Right now with so many campaigns like #MeToo and #TimesUp, there's no better time to continue to shine a light on women feeling empowered and people supporting them."

Ellen PompeoIn January, it was revealed that the "Grey's Anatomy" star had signed a deal making her the highest-earning actress in dramatic TV, and she gave an interview in which she extolled the virtue of knowing one's worth.

"Now, maybe it's my Irish Catholic upbringing, but you never want to [be perceived as] too greedy. Or maybe it's just that as women, that's our problem; a guy wouldn't have any problem asking for $600,000 an episode. And as women, we're like, 'Oh, can I ask for that? Is that OK?' I'd call [series creator] Shonda [Rhimes] and say, 'Am I being greedy?'" Pompeo told The Hollywood Reporter. "I'm 48 now, so I've finally gotten to the place where I'm OK asking for what I deserve, which is something that comes only with age."

Julia Louis-Dreyfus"Because I had children when I was working, there were a lot of things I didn't do because I didn't want to travel. Had I made different choices, my career would have gone another direction, but then I wouldn't have been able to look after my kids in the same way. I feel very lucky, knowing that nothing is perfect. And you can't have it all," the "Veep" star told Health magazine in 2013. "You can't have it all. That's absurd! It doesn't mean you shouldn't pursue what you desire. It's not possible to do and have everything all the time. So you have to make choices. And I don't think that's an anti-feminist statement. I don't mean you have to sacrifice who you are or cower in a corner because of some stupid-ass glass ceiling. But if you realize that, then I think you can free yourself up to prioritize."

Mindy KalingWhen asked about advice for those pursuing a career in the arts, the "Mindy Project" creator told The Huffington Post: "Develop a thick skin early on! And to quote Aaron Burr from Lin-Manuel Miranda’s 'Hamilton': 'Let me offer you some free advice. Talk less.' So much of what we are taught as young women is that self-expression is the most important thing. I think being perceptive is the most important thing. What can we learn from looking outside of ourselves and our own experiences? That’s made me a better writer, and a better actor.”

Amy PoehlerThe former "Parks and Rec" star said in a 2011 Harvard commencement address that it was important to "be open to collaboration."

"Other people and other people's ideas are often better than your own. Find a group of people who challenge and inspire you, spend a lot of time with them, and it will change your life. No one is here today because they did it on their own," she said. "You're all here today because someone gave you strength. Helped you. Held you in the palm of their hand. God, Allah, Buddha, Gaga—whomever you pray to."

Michelle ObamaIn her final address as First Lady, Obama encouraged young people to be brave.

"Don't be afraid. Be focused. Be determined. Be hopeful. Be empowered. Empower yourselves with a good education, then get out there and use that education to build a country worthy of your boundless promise," she said. "Lead by example with hope, never fear. And know that I will be with you, rooting for you and working to support you for the rest of my life."

Beyoncé"It's really about changing the conversation. It's not about perfection. It's about purpose," the singer told Elle magazine in 2016. "We have to care about our bodies and what we put in them. Women have to take the time to focus on our mental health—take time for self, for the spiritual, without feeling guilty or selfish. The world will see you the way you see you, and treat you the way you treat yourself."

Shonda Rhimes"If I ask a guy writer on my show what he wants to be, he'll say, 'I want to run my own show or take over a network.' Female writers answer, 'Oh, I want to work for somebody great and really learn.' I yell, 'Don't ever say out loud again that you're going to dream small!'" the Shondaland founder told Cosmopolitan in 2015. "So many women look for permission. Men don't — they just do it. Decide the only person whose opinion matters is yours. Don't be a sociopath about it, but stop worrying people are going to think you 'like yourself too much.' Please, God, like yourself too much!"

Lady Gaga"I feel sad when I'm overworked and I just become a moneymaking machine and my passion and creativity take a backseat. That makes me unhappy," the singer said in a 2011 address. "So what did I do? I started to say no. 'I'm not doing that.' 'I don't want to do that.' 'I'm not taking that picture.' 'I'm not going to that event.' 'I'm not standing by that because that's not what I stand for.' And slowly but surely, I remembered who I am."

Viola Davis"What I've been telling my daughter lately is to stop apologizing," the "How to Get Away With Murder" star said at the Time 100 Gala in 2017. "I think that women, we're at this huge kind of point in our lives, in history, where we need to step into our power and not give it over to anyone or apologize for it. And understand that in whatever we do, we deserve to be there and we deserve to have a voice."

Jennifer LopezThe performer told Body Lab in 2015 that her advice to women would be: "Be true to yourself. To love yourself fully and completely be the best happiest healthiest version of yourself."

Reese Witherspoon"Speak up, even if your voice shakes," the actress told Man Repeller last year.

Jennifer AnistonWhen asked by Glamour in 2013 what she'd tell her 30-something self, the actress said: "Go to therapy. Clean up all of the sh-t. Clean up all of the toxins and the noise. Understand who you are. Educate yourself on the self."

Kerry Washington"Make sure that your dreams are yours," the "Scandal" star said in 2016. "Make sure you're not pursuing the dreams that somebody thinks you should have, because dreams take a lot of work and a lot of support, and you'll be more inspired to go after them if they're really, really yours."

Ava Duvernay“Work without permission,” the director said in a video posted on Twitter. “So many of us work from a permission-based place, and we don’t even know it. We are waiting for someone to say it’s OK, waiting for someone to give us the greenlight, give us money, tell us how to do it, shepherd us through and if you're waiting for that, some people get lucky, but most of us have to do it for ourselves."

Meryl Streep“For young women, I would say, don’t worry so much about your weight. Girls spend way too much time thinking about that, and there are better things," she told Indianapolis Monthly in 2014 when asked to give young performers advice. "For young men, and women, too, what makes you different or weird, that’s your strength. Everyone tries to look a cookie-cutter kind of way, and actually the people who look different are the ones who get picked up. I used to hate my nose. Now, I don’t.”

Nicole Kidman“Particularly for a young girl, it’s ‘Take care of yourself, make sure you are protected, don’t let anyone break your spirit and be yourself,'" Kidman told the Press Association last year, according to InStyle. "So much of the time we model ourselves and our identities on what we see, and actually finding who you are and what you want to say and what your voice is, is one of the hardest things to do, but one of the most important things to do."

Kate Hudson"Your friends' success is as important as your own, and we need each other to cheer-lead each other," the actress told Vanity Fair last year. "Jessica [Alba] is someone, we talk a lot about business, because our businesses have grown very quickly and very fast. It was a learning curve for both of us. Sometimes it’s sharing experiences, like, 'Did you ever think we’d be in this position?' She had an idea and it came to fruition and grew so fast—and same with me. We do talk about the learning curve and how fast we had to rise to that challenge.”

Jessica ChastainThe actress told Marie Claire last year that the best career advice she'd ever received was "to not follow the money, but to follow the education of projects."

Priyanka Chopra“I think to be able to be a producer or director, or any other vocation you might want to take on, it’ll be a fight, and you’ve got to not be afraid of it," she told Buzzfeed last year. "There’ll be people who’ll want to pull you down, there’ll be people who say things about you that may not be true at all just so you feel small, so you don’t become the best that you are, but you just have to dust off your detractors and keep going. I think that’s very important for any woman."