Sheryl Sandberg: 'I will never make another joke about growing old again, ever'

In May 2015, Sheryl Sandberg's husband Dave Goldberg died suddenly.

Her second book, "Option B," opens with his death. Along with research presented by coauthor Adam Grant, it goes on to share the Facebook exec and mom's experience working through her grief.

In an episode of Business Insider's podcast "Success! How I Did It," Business Insider US editor in chief Alyson Shontell asked for Sandberg's best advice on building resilience, which Sandberg has previously compared to a muscle that strengthens with exercise.

"Two things that I think matter are gratitude and joy," Sandberg said.

"It's ironic but going through the worst thing of my life, this huge tragedy, made me more grateful. It never occurred to me Dave wouldn't hit age 48 or wouldn't live to be 50, as he would have turned this year," she continued. "I will never make another joke about growing old again, ever. No one else should either. Because we either grow old or we don't."

She went on to share: "Every day, every week, every month, every year is a gift. That doesn't mean we can remember it all the time, but when things are hard, remembering how lucky we are to be just alive brings a lot of meaning into our lives."

To build gratitude, Sandberg does a daily exercise suggested by Grant: Before she goes to bed, she writes down three moments of joy every day - even as small as an enjoyable cup of coffee. As she got in the habit of writing them down, she told Shontell, those moments became more meaningful to her, and she started to notice them more on a daily basis.

"I realized that before Dave died, I went to bed every night worried about what was wrong and what I was going to mess up on the next day," she said. "I don't think I was living to its fullest. I don't think I was grateful for that day or looking for the joy. Now, I'm trying. I can't say I do it every day, but I am trying to be grateful for each day and look for joy."

Listen to the full podcast interview: