Sheryl Sandberg, COO of Facebook, coaches young women to "lean in" to their careers. Erin Callan, former Lehman Brothers CFO, warns against single-minded careerism, citing her own challenge in trying to have her first child at age 47. Susan Patton advises Princeton women to search for husbands while on campus.

What is a twenty-something who wants to be successful in her career and family life to do? What do the stories, advice and warnings all add up to?

Too often, not that much: Most popular discussion on the "can you have it all" question really just highlights the many challenges women face, rather than offering any solutions. Young women are left worrying that we won't be as happy or succeed as much as we could if we don't make the right decisions, but hear little concrete advice about what steps to take in our 20s.

Women confused by the conflicting life advice should invest 15 minutes in watching a talk, available online through the nonprofit organization TED, by Dr. Meg Jay, called "Why 30 is not the new 20." Jay, a clinical psychologist, assistant professor at the University of Virginia, and author of The Defining Decade: Why Your Twenties Matter — and How to Make the Most of Them Now, offers practical advice to help women in their 20s become the women they want to be in their 30s, 40s and beyond.

The bottom line from Jay's talk is that the decisions we make in our 20s matter. Jay debunks the popular idea that the 20s are an extended adolescence. As Jay puts it, the 50 million twenty-somethings in the U.S., which is about 15 percent of the population, deserve "to know what psychologists, sociologists, neurologists and fertility specialists already know: that claiming your 20s is one of the simplest, yet most transformative, things you can do for work, for love, for your happiness, maybe even for the world."

More than a time of transition, waiting for one's life to begin, it's a time for building a strong foundation. Jay points out that the first 10 years of a career traditionally has a big impact on career earnings; more than half of Americans are with their future partner by age 30; female fertility peaks in our 20s; and, the brain ends its last growth spurt in our 20s. As Jay explains:

"Thirty is not the new 20, so claim your adulthood, get some identity capital, use your weak ties, pick your family. Don't be defined by what you didn't know or didn't do. You're deciding your life right now."

This sounds like a lot of pressure. Some may find comfort in the idea that the 20s are a period of extended adolescence. Kay Hymowitz called it a new "pre-adulthood" stage in her book, Manning Up: How the Rise of Women Has Turned Men into Boys. Others have favored the terms "twixters" and "kidults." Millennials have been labeled the "boomerang generation," leaving home for college only to return after graduation.

Yet rather than embrace these titles and the prognosis that our generation procrastinates growing up, Millennials should think about where this leads, specifically the impact that the delay in moving forward in our careers and in finding a spouse has on our future ability to "have it all" as so many want.

Real changes can be made. Hooking up, for example, might seem harmless in college, but continuing to do so into the 20s too often delays the real search for a spouse. Job and educational opportunities should be evaluated on the doors they will open going forward, rather than on how they fit with one's desired lifestyle today. It takes time to build the lives we want and to find the person with whom we want to build that life.

We need to act now to take steps toward becoming the adults we want to be. Not when we reach 30, 40 or some other supposedly magic age when everything will just work out.

Young women will continue to hear endless advice from elders. Politicians, business leaders and celebrities — including President Barack Obama, Melinda Gates and Oprah Winfrey — are speaking at various graduation ceremonies across the country. Most will offer little more than humor, personal stories and words of congratulations. Graduating seniors would be wise to watch Jay's talk as their first serious post-graduation decision, and remember they can't wait for life to begin in their 30s. It's happening now.