By now, many of you have seen the viral video sent by Rob Lowe to an Austin-woman battling lung cancer.

"I'm sending prayers for you, and thinking of you. I know you're in a really tough fight," Lowe said to 48-year old Alex Charpentier, in the minute-plus long clip.

The video, coming just in time - as Charpentier was in the final days in her battle against Stage 4 lung cancer.

She first noticed something was off during a routine exercise.

"(Alex was) playing tennis, and just lost her breath, and just couldn't catch it back again," explained her younger sister Joanna Gorin.

At first, she was diagnosed with pneumonia. But at the urging of friends, she returned for further testing.

"And then she went back and basically got the diagnosis a few weeks later that she had lung cancer," Gorin explained.

By the time she was diagnosed, it was already Stage 4 and had spread throughout her body. The news, coming as an absolute shock to a woman who never smoked in her life.

The American Cancer Society estimates 16,000-24,000 non-smokers die each year from lung cancer, a startling statistic around a disease with a societal stigma. In Alex's case, it was a genetic mutation.

"I don't think until the day that they told her that she was not going to survive this shortly before she actually passed away that she was going to beat this," said Gorin.

Charpentier was the oldest of three sisters, which along with their mother, Gorin affectionately dubbed "the Gorin girls." A year before being diagnosed, their mother was killed in a car accident. Through that loss, Charpentier took her role as big sister to a new level.

"Before she passed away, she said to me she'll always be my big sister, and she always will. I may be the older sister now, but I'll never be the big sister - that's always her," Gorin said, as she fought back tears.

While Charpentier had initial success with treatment, its effectiveness soon faded. A mother of two - with close relationships to her sisters - she passed along her final wish.

"She said 'Absolutely, this has been a great life.' But the one thing she wanted was to meet Rob Lowe," said Gorin.

With help from a friend, that wish was granted.

"All my love. I'm thinking about you," said Lowe.

Shortly after receiving the video, Charpentier responded with one of her own.

"When my friends showed the video to my kids, they cried because they know how much this means to me," Charpentier said.

A few days after receiving that video - Alex passed away. But the attention it received, gave her a whole new platform.

"She was someone that wanted to live a life that had a positive impact on everyone around her. And to know that her death could do that, would be the best gift," Gorin said.

As she battled her disease, Charpentier worked with the Bonnie J. Addario Lung Cancer Foundation, an organization working on a cure for lung cancer.

“Alexandra was so young and it breaks my heart that she passed away. She was a beautiful example of how hard a mother will fight to raise money for lung cancer awareness and research, so that fewer children will have to say goodbye to their mothers too soon” said Bonnie J. Addario, who founded the charity. “Alexandra’s fund raising page is still active and we will continue doing what she wanted us to do – turn lung cancer into a chronically managed disease by the year 2023.”

And if she can raise awareness with a little help from Rob Lowe, all the better.