Often we hear the sweet old saying, "I wish I knew then what I know now."

Arianna Huffington shares with us what she wished she knew in her twenties. Lucky us—we get to hear the wisdom now, direct from the wisest and most sophisticated source.

Listen up, ladies! This is better than gold.

1. How we talk to ourselves matters. Even our worst enemies don't talk about us the way we talk to ourselves. I call this voice the obnoxious roommate living in our head. It feeds on putting us down and exploiting and magnifying our insecurities and doubts. I wish someone would invent a tape recorder that we could attach to our brains to record everything we tell ourselves. It would shock us to hear it played back.

2. There is a purpose to our lives, even if it is sometimes hidden from us, and even if the biggest heartbreaks only make sense as we look back, rather than as we are experiencing them. So we might as well live life as if—as the poet Rumi put it—everything is rigged in our favor.

3. It's so important to occasionally disconnect from all your devices and distractions and reconnect with yourself. (My past self might have been confused by this warning from my future self, since iPhones and BlackBerrys didn't exist when I was in my twenties, but it's still a very important point.)

4. The world will provide plenty of insistent, flashing, high-volume signals directing you to make more money and climb higher up the ladder. But there will be almost no worldly signals reminding you to stay connected to the essence of who you are, to take care of yourself along the way, to reach out to others, and pause to wonder.

5. Someday you're going to cofound something called a website, and it is going to come alive to mixed reviews, including some very negative ones. When this happens, remember what mom told you: "failure is not the opposite of success, it's a stepping stone to success." And don't hold grudges against those reviewers, or anyone—it's one of the most draining things you can do. Indeed, as Carrie Fisher said, "Resentment is like drinking poison and waiting for the other person to die."

6. We are not put on this earth just to accumulate victories and trophies and avoid failures; but rather to be whittled and sandpapered down until what's left is who we truly are.

7. Not only is there no tradeoff between living a well-rounded life and high performance, your performance will actually improve when your life includes time for renewal, wisdom, wonder and giving. Taking this advice will save you a lot of unnecessary stress, burnout, and exhaustion!

8. Get thirty minutes more sleep than you are getting now (unless you are so wise you are already getting all the sleep you need), either by going to bed earlier or by taking a short nap during the day—or a combination of both. You have an opportunity to immediately improve your health, creativity, productivity, and sense of well-being.

9. Drop something that no longer serves you. (I did a major "life audit" when I turned forty, and I realized how many projects I had committed to in my head—such as learning German and becoming a good skier and learning to cook. Most remained unfinished, and many were not even started. Yet these countless incomplete projects drained my energy and diffused my attention. As soon as the file was opened, each one took a little bit of me away. It was very liberating to realize that I could "complete" a project by simply dropping it—by eliminating it from my to-do list. Why carry around this unnecessary baggage? That's how I completed learning German and becoming a good skier and learning to cook and a host of other projects that now no longer have a claim on my attention.)

10. "No" is a complete sentence.

And so it is. I am off to drop some projects, disconnect from my devices, talk more kindly to myself and wonder at the marvels of the world (there are many when you pause and look). But first, a nap. Thanks for the wisdom, Arianna!

Arianna Huffington is the chair, president, and editor-in-chief of the Huffington Post Media Group, a nationally syndicated columnist, and author of fourteen books. 

In May 2005, she launched The Huffington Post, a news and blog site that quickly became one of the most widely-read, linked to, and frequently-cited media brands on the Internet. In 2012, the site won a Pulitzer Prize for national reporting.

 She has been named to Time Magazine's list of the world's 100 most influential people and the Forbes Most Powerful Women list. Originally from Greece, she moved to England when she was 16 and graduated from Cambridge University with an M.A. in economics. At 21, she became president of the famed debating society, the Cambridge Union. 

She serves on several boards, including HuffPost's partners in Spain, the newspaper EL PAÍS and its parent company PRISA; Onex; The Center for Public Integrity; and The Committee to Protect Journalists.

 Her 14th book, Thrive: The Third Metric to Redefining Success and Creating a Life of Well-Being, Wisdom, and Wonder was published by Crown in March 2014 and debuted at #1 on the New York Times Bestseller list.

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