Paris, France (CNN) -- In 2009, bottled water company Evian decided to focus its advertising strategy on an association with youth.
It took almost a year for Mercedes Erra to convince the company that a commercial featuring babies roller skating to hip hop classic "Rapper's Delight" was the best way to get that message across.
But happily for advertising guru Erra, "Roller Babies" became the world's most-viewed brand video. It was viewed online more than 75 million times and shared almost 2.2 million times -- a Guinness world record.
Erra founded ad agency BETC Euro RSCG in 1995 with three others. Today, she is also managing director of communications group Havas and executive president of its marketing arm Euro RSCG Worldwide.
BETC is now one of the largest and most awarded agencies in France, with a client roster that includes more than 80 of the world's top 100 largest advertisers, including Coca Cola, IBM, Volvo, Disney, LVMH and McDonalds.
Erra is a progressive and, at times, challenging force in French life: A mother to five sons campaigning for greater participation by women, she is on the board of the Elle Foundation, the Committee on the Image of Women in the Media, and Force Femmes, and is president of the Women's Forum for the Economy and Society.
A Spanish-born Officier of the Legion d'Honneur (motto: "Honour and Fatherland"), Erra is pushing for diversity in a society not always famed for its racial tolerance. She is on the board of the French Immigration Museum, and is a member of Human Rights Watch and UNICEF.
Erra began her career in advertising in 1981, as an intern at Saatchi & Saatchi. She believes she distinguished herself there by seeking out more and more responsibility, ultimately becoming managing director.
"I think when people want responsibility, they can have it immediately because (most) people don't want responsibility," she said.
Although she disavows any particular skill other than taking responsibility, colleagues say Erra has a rare combination of rigorous business analytics, and a strong intuition about how consumers will react.
Here she talks to CNN's Leading Women about immigration, the glass ceiling and what's most important in life and in work.
On being a migrant ...
I was born in Barcelona. I arrived in France when I was six years old. I lost my country and quality of life. We had a little money in Spain, but nothing in France.
Those two changes were difficult but at the same time very positive. When you are six, you learn a lot if you change your country. You learn relativity; you learn the world is complicated. You become more mature.
I experienced that life is not easy -- I think today sometimes life is too easy -- and I never forget this.
On "women's work" ...
When I was young, my mother was at home and my father worked and it was not easy. By the end of the day, she would dream of working outside the home, and my father would arrive and say, 'I am so tired.'
I remember her saying, 'Nobody wants to do housework, nobody says thanks, nobody gives me money,' and she's right. In my mind, my mother was doing a job, and I said to myself, 'I don't want that job.'
When I began working, it was a pleasure. And sometimes when I have meetings with very important men, and they say 'I am tired,' I say, 'We get money; it's very interesting. Stop. Please, stop.'
On the glass ceiling ...
More than a glass ceiling, the obstacle for women is their own minds. I get the feeling that if a woman is very clear, it's very difficult to prohibit something. It was impossible to stop me.
Many things have to change. But first, it's very simple: Girls need to think about having a good job and doing the same kind of studies as boys.
In France, we have the Baccalaureate (high school diploma). In mathematics, the best results? The girls. And when they choose (further) studies? No girls in mathematics. Why? Because they think they are not the best.
I think we have to be clear, the objective is not to be the best, it's to do what they want -- but they can want everything.
On work-life balance ...
I don't want all women to do what I do. I have a lot of energy -- not a normal amount, I know. I sleep very few hours and not all women can get by on three hours a night.
I am not balanced -- I have more energy than balance.
Some people have their work and their home life and don't want interaction between them. I don't have two lives. I have no problem having people come to my house to work, because I like these people. It's difficult for me to have different relations with people who I work closely with. These are very important people to me.
On working with big-name clients ...
With people who are important, I am more difficult to work with, because I am not impressed (by their reputation). I am impressed when people are very clever or very nice or have a very strong heart or a strong intuition.
On doing what you love ...
Do things well, and do what you like to do. It's bad to do something because you think other people will consider you clever.
I have strong views on this because when I speak with my gardener, she is so clever, but it's a different kind of clever. It's not the same as my way of being clever, but it's still clever.
Do what you think is right for you, and remember: Don't lose half your life to things that are not interesting to you. I am disturbed by what people will accept.
Some people have less opportunity, but if you can choose what you do, you are a winner.