Beyond angst and self-doubt, the younger Alba had another thing in common with these girls: She grew up on a military base. After getting the news that Alba’s 18-year old mom was expecting, her father joined the U.S. Air Force to provide for his family. The actress-turned entrepreneur spent time living in Biloxi, Mississippi, before settling in Del Rio, Texas, at the Laughlin Air Force Base. When Alba was nine, her father left the military, moving the family to Southern California. The transition was tough. “Everyone on the base becomes your family… The girls in [Inland Empire] weren’t that nice,” she said. And she missed the base’s Post Exchange. “It had everything!”

Her family lived modestly—they drove a hand-me-down Buick Regal that “always backfired,” she remembered—but a local contest, which Alba won, paid for acting classes.  Alba’s first gig got her a Screen Actors Guild card and kick-started her career.

Read the full transcript of Jessica Alba’s interview

Though her life seems a fortuitous turn of events, Alba wasn’t always happy as a teen. “I had this vision, and obviously aspirations for who I wanted to be, and I wasn’t really sure how I was going to get there,” she told the audience of teenagers. She had difficulty relating to her peer group, and also struggled to find the roles she craved. “I wanted to project the women that I grew up with, a multicultural sort of woman, diverse in thought, as strong as a man but still a woman, and gosh darn it, I wanted to be a superhero.”

Alba’s dream came true when she was cast as Max Guevara in Dark Angel, a television drama featuring supernatural characters fighting in a post-apocalyptic United States. She then went on to play Susan Storm in the Fantastic Four, a blockbuster about a quartet of superheroes.

Yet around 26, Alba found herself restless. “I sort of went through a midlife crisis,” she said. “I became quite introspective and reflective about my life and my choices and my family and work and everything. I got pregnant at 26 as well, and really my daughter was such a blessing… A lot of turmoil that I had just sort of like melted away, and I was like, oh, this is what I should be doing.” After her child was born, she read Healthy Child, Healthy World and was appalled by the truths it uncovered, like the amount of toxins and chemicals in everyday products – from no-tears soap to a bedroom mattress. Alba wished there was a company that made these products without toxins – and the seed for The Honest Company, Alba’s eco-friendly company, was born.

Alba, who has two daughters, calls the project her “third baby.” It took three-and-a-half years before finding the right mix of partners. (“I had a lot of people slamming a door in my face and telling me I was nuts, and there was no way that anybody could do this,” Alba said.) Today, Honest has 63 employees and offers a wide array of products – from diapers to detergent. Alba’s husband Cash Warren was her rock during the dark, startup days; he helped her hone in and focus on the business, encouraging her to move forward with her idea.

“Partner with people that are smarter than you, understand your strengths and weaknesses, and surround yourself with people that complement your strengths, but could support your weaknesses,” Alba, a 2012 Fortune Most Powerful Women Entrepreneur,  said – advice that’s led to her professional and personal success.