This time of year, it’s common for commencement speakers to share with new graduates what they’ve learned in life.

On Saturday, while addressing graduating students at the University of California at Berkeley, Sheryl Sandberg flipped the script and instead offered a poignant and fiercely candid speech about what she has learned in death.

It was the Facebook chief operating officer’s first public comments about the death last year of her husband, David Goldberg – a Silicon Valley fixture and the chief executive of SurveyMonkey – who died unexpectedly while the couple was vacationing in Mexico.

“Dave’s death changed me in very profound ways,” she told the school’s 4,700 graduating seniors. “I learned about the depths of sadness and the brutality of loss. But I also learned that when life sucks you under, you can kick against the bottom, break the surface and breathe again. I learned that in the face of the void — or in the face of any challenge — you can choose joy and meaning.”

Sanberg said she was sharing her story in hopes that graduates would leave with new lessons about hope, strength “and the light within us that will not be extinguished.”

Adversity is unavoidable, she told graduates, but how you overcome challenges is more personally defining than achievement.

On Mother’s Day, Sandberg posted an emotional message on Facebook outlining how her husband’s death led her to realize the difficulties single mothers face in raising children, even without financial burdens. Since the early 1970s, she noted, the number of single mothers in the United States has nearly doubled.

“Before, I did not quite get it,” she wrote. “I did not really get how hard it is to succeed at work when you are overwhelmed at home. I did not understand how often I would look at my son’s or daughter’s crying face and not know how to stop the tears. How often situations would come up that Dave and I had never talked about and that I did not know how to handle on my own. What would Dave do if he were here?”

Sandberg circled back to some of those challenges on Saturday, recalling how she struggled with her children’s grief and initially blamed herself for her husband’s death

“I poured over his medical records asking what I could have — or should have — done.”

She said she eventually realized that not taking failures personally allows people to recover and even thrive.

Her husband’s death, she said, was one of many challenges she has endured in life, many of which left her feeling like a “massive failure.” Sandberg recalled being unprepared during her first job out of college and worrying about being fired. She discussed failed relationships that crushed her, including her first marriage, which ended in divorce.

“One day my friend Adam Grant, a psychologist, suggested that I think about how much worse things could be,” Sandberg told the graduates. “This was completely counterintuitive; it seemed like the way to recover was to try to find positive thoughts. ‘Worse?’ I said. ‘Are you kidding me? How could things be worse?'”

Sandberg added: “His answer cut straight through me: ‘Dave could have had that same cardiac arrhythmia while he was driving your children.’ Wow. The moment he said it, I was overwhelmingly grateful that the rest of my family was alive and healthy.”

Sandberg said the “greatest irony” of her life is that losing my husband helped her appreciate life. She pointed out that she is not without “a huge reservoir of sadness,” one that is with her at all times.

“I never knew I could cry so often — or so much,” she said.

But, she added, that for the first time in her life she is grateful for “the gift of life.” Sandberg said she celebrates more and — instead of going to sleep obsessing over a long list of that day’s mistakes — she tries to focus on moments of joy.

Beyond appreciating her life more, Sandberg urged graduates to build resilience in themselves.

“When tragedy or disappointment strike, know that you have the ability to get through absolutely anything,” she said. “I promise you do. As the saying goes, we are more vulnerable than we ever thought, but we are stronger than we ever imagined.”