Story highlights In her new book, Facebook's Sheryl Sandberg says women must demand more at work

Wendy Sachs agrees, saying women often "give it up for free" in the workplace

Not demanding a competitive salary was a huge mistake for TV host Mika Brzezinski

Brzezinski says asking for more at work can have a domino effect on one's self-worth

I often feel like a high-class prostitute, I just don't charge like one. Call girls seem to know their black book value, or at least their madams do. But sadly, many professional working women don't get or demand the compensation they deserve.

It begins after college when young women are already making less than the guys -- 82% of what their male peers receive , according to a recent study by the American Association of University Women. It gets worse over time, particularly for women who temporarily take themselves out of work by choice or necessity when they become moms. This chronic feeling that they are giving it up for free can hurt women's lifelong earning power and their self-esteem.

Facebook COO Sheryl Sandberg wants to give America's women workplace moxie and the skills to break through barriers that are holding them back, namely themselves. Sandberg's new book, "Lean In: Women, Work, and the Will to Lead," is already generating the kind of buzz-worthy backlash and controversy that brings out the schadenfreude from the entire political rainbow of female commentators. Because she's a billionaire and home for dinner with the kids at 5:30 , her gilded life makes her hardly relatable to virtually any other working mom.

The book, together with an ambitious "Lean In" social movement of monthly meetings dosed with inspirational anecdotes from other women, is all about bringing on the girl power and getting us out of the cubicle and into the corner office. "Lean In" comes ironically on the high heels of Marissa Mayer , the 30-something, newly minted Mama Bear CEO at Yahoo! who pulled the plug on the flex policies that allowed employees to work from home. Mayer, who has a nursery for her own newborn in her office, is getting hazed for this seemingly retro and anti-family move. Is Mayer the ultimate sellout or the quintessential feminist? Well, depends who you ask.

But have no doubt, working women are back on the political radar. President Obama gave a shout out to the cause of equal pay at his recent State of the Union. The White House also has created several initiatives in the wake of Obama signing the Lilly Ledbetter Fair Pay Act in January 2009, the first law he signed in his administration. The law amends the Civil Rights Act, extending the period women can sue for gender pay discrimination.

So why do so many accomplished women get snared in the vicious cycle of not getting paid properly for the work they do? The problem, Sandberg's book points out, is internal. Women can get squeamish about negotiating for money and don't know how to effectively advocate for themselves. We are hard wired to make nice, not make people uncomfortable. Discussing money, for many women, feels exceptionally awkward.

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In my zigzagging career as a TV producer, writer, PR strategist, website editor-in-chief and TV spokesperson, I have cut my rates, jumped at the first offer, and even worked for free. Sometimes, I've just felt lucky to get the job.

This behavior, said Mika Brzezinski, the best-selling author of "Knowing Your Value: Women, Money and Getting What You're Worth" and co-host of MSNBC's "Morning Joe," is not unusual for women, but it's disastrous. It undermines our value. She said we must stop feeling grateful and instead become fierce and focused. Work hard and go after what you deserve.

Brzezinski's book was born from personal experience and her admitted failure of not cutting herself a fair deal and getting the money she deserved. At the time, Brzezinski's on-air TV career had stalled, and when she landed the gig at "Morning Joe," she never negotiated. Barely making ends meet and hearing she was earning 14 times less than her co-host, Joe Scarborough, was depressing and painful. After all, Brzezinski was working her tail off on "Morning Joe," helping take it from an unknown MSNBC show to a political commodity. Like so many women, Brzezinski thought if she worked hard, she would eventually be rewarded. But her paycheck left her defeated and bitter. Brzezniski eventually got a significant raise. But she was prepared to quit the show when MSNBC finally came to the table.

"We are good at advocating for other people but not for ourselves. You are asking not for the money you need, but the money you deserve," said Brzezinski. "It's a cop out to say this just happens to women. We have to step up and take what we want and not feel uncomfortable for it. No drama, no games, no whining. Make them need you and be ready to walk."

Lyss Stern , founder and president of Divamoms.com, a luxury lifestyle company for mothers in the Tri-State area, said she knows what it's like to not be taken seriously. Because of her extensive network of influential and affluent moms -- an important demographic -- Stern's company is highly sought after by consumer product brands, entertainment companies and fashion and beauty businesses around the country. But it has been frustrating for Stern to get men, often the people making the deals, to recognize the value of her company.

"I've found that it's the men who think they can get away with not paying for my work. To them, they see a mom company as a hobby, not a business," Stern said. "I have multi-million dollar companies reaching out to me each day. They will take out a $100,000 ad campaign in The New York Times, but e-mail me and say they want to do business but have no real money to budget for me. It's insulting."

In business for nearly a decade, it was relatively recently that Stern's attitude changed and she had the confidence to politely walk away from a lousy deal.

"It took me seven years to truly understand the worth of my brand and to be able to say that if you don't take me seriously, I don't want to work with you. It's your loss," Stern said.

But many women simply lack the mojo to say no. It's almost as if women are conditioned to be pleasers and say yes, even if it's not lucrative for them. They depreciate their own value just to get the work but are then resentful that they've sacrificed themselves.

"It's a vicious cycle. All of a sudden 20 years go by and you realize, wait, I'm supposed to be making more not less, what happened?" said Brzezinski.

She said that getting what you deserve at work can also have a domino effect on all areas of a woman's self worth.

"It changes your life to know your value and every relationship you have is better and stronger and more rewarding and lasting," Brzezniski said. "Women end up sabotaging their relationships when we don't demand respect for our value from other people."