The next time you feel like giving up, take inspiration from Sheryl Sandberg's story.

Sheryl has been the No.2 at Facebook for 12 years. She's helped build the company to $545 billion in size. She's been the voice of calm through the company's recent challenges - and it's because of what she has endured outside the business that has made her so strong inside.

Four years ago, in May 2015, her 47 year old husband and CEO of SurveyMonkey, Dave Goldberg, suddenly died of a heart attack while exercising in a gym.

Sheryl says, “We were at a friend’s fiftieth birthday party in Mexico. I took a nap. Dave went to work out. What followed was the unthinkable - walking into a gym to find him lying on the floor, flying home to tell my children that their father was gone. Watching his casket being lowered into the ground.”

Two weeks after he had died, Sheryl cried, “I want Dave.” A friend said to her, “Option A is not available. So let’s just kick the sh*t out of Option B."

Determined to move forward, Sheryl wrote down everything she was feeling in a journal. She recalls, “I wrote and I wrote and I wrote. Literally all I did was my kids, come to work and write.”

Two years later, she used what she wrote to publish her book: "Option B."

The book, subtitled "Facing Adversity, Building Resilience, and Finding Joy" has gone on to impact hundreds of thousands in grief or facing adversity.

She says: “Dave’s death changed me in very profound ways. 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.”

“It is the hard days, the times that challenge you to your very core, that will determine who you are. You will be defined not just by what you achieve, but by how you survive.”

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

When things get tough, do you let those moments break you or build you?

When you're at zero, do you give up or get up?

Sheryl’s advice echoes the words of another great entrepreneur, Steve Jobs:

“Remembering that I'll be dead soon is the most important tool I've ever encountered to help me make the big choices in life.”

“Almost everything - all external expectations, all pride, all fear of embarrassment or failure - these things just fall away in the face of death, leaving only what is truly important.”

“Remembering that you are going to die is the best way I know to avoid the trap of thinking you have something to lose. You are already naked. There is no reason not to follow your heart.”

When you have nothing to lose, you have everything to gain.

Life is precious. Live it fully.