Our national health crisis has been especially dire for African-American women.

Nearly half have heart disease and 40% have high blood pressure, according to the American Heart Association

Their risk of stroke is almost twice that of white women, reports the CDC

They are more likely to die at a younger age than women of other ethnicities, the heart association said.

Vanessa Garrison and T. Morgan Dixon refuse to accept this future, and formed the nonprofit GirlTrek to reclaim their health through walking.

T. Morgan Dixon, left, and Vanessa Garrison founded GirlTrek.

"It wasn't because we were walking enthusiasts or because we love to walk. When we started we were just trying to save our own lives," Dixon said.

"How do we not fall in these pitfalls that our mothers and our aunts and our grandmothers have fallen into? Eighty percent of us are overweight and carrying that weight is killing us now at disproportionate levels. We can't do it anymore. We can't carry it anymore."

A GirlTrek walking team in Charlotte, North Carolina.

More than 170,000 women have laced up with GirlTrek and formed walking teams across the country. GirlTrek's goal is to get 1 million women to take its pledge by 2020 -- walk 30 minutes a day. The activity can help fight diabetes and reduce the risk of heart disease, stroke and dementia.

Changing a culture of self-sacrifice

Vanessa Garrison believes the group's mission is more than just increasing lifespan. Quality of life is just as important, but in order to reach women in her community, she said she knows they must overcome a cultural mindset.

Walkers in Charlotte, North Carolina want to be role models.

"We grew up in households where our mothers and grandmothers and our aunties always chose to come last; they would always push those extra couple of hours to give to their family. And we've modeled that behavior and in fact we celebrated that behavior and it is the only way we knew how to navigate this world and get by. We created entire identities around our service to others." Garrison told CNN.

"And I tell you it is OK for you to put yourself first today for this 30 minutes and then in fact when you do that your family becomes more powerful, your community becomes more powerful."

It is important, Garrison said, for girls to see their mothers as healthy role models.

"That is actually how you shift the entire dynamic of a culture by creating the habits that get passed from one generation to another," she said.

Zakiyyah Smith takes part in the RoadToSelma event in Los Angeles.

Reaching these girls is an essential goal of GirlTrek. Studies show the youngest generation of African-American girls now have the highest chance of developing diabetes.

Creating a sisterhood

GirlTrek continues to grow thanks to the 1,000 organizers who put together all the local walks and the participants who pledge to bring along a sister.

"Women are connecting with their neighbors, their friends, the women at their church, the women on campuses, and when you walk you talk," Dixon told CNN.

"And so it becomes a support community where women who are alone or women who are suffering any kind of depression or anxiety or stress can walk, talk and slow down with friends. And that act of slowing down is radical."

GirlTrek follows the path laid by the civil rights movement as both a guiding principle and often as actual routes to take. Last year, they walked the 100 miles to freedom along the Harriet Tubman Underground Railroad Byway. This year, they have launched the nationwide yearlong "Road to Selma" event.

The organization and its walkers find inspiration in heroines like Harriet Tubman. New walkers receive Harriet's Handbook, which provides 1,000 walks and a step-by-step guide to help women stay motivated.

"We know that when black women walk, things change, and that we walk in the footsteps of that legacy," Garrison said, recalling African-American civil rights activists

"And when we tell that story to women they see themselves in those names. They see themselves as the next Ella Baker, the next Fannie Lou Hamer, the next Septima Clark, the next Harriet Tubman and they are inspired by their history to start walking and create change in their communities."

A GirlTrek walking team in Detroit.

This change goes beyond getting in shape. When a walking team takes to the streets, they coalesce around problems they see or causes they discuss. Already empowered by the changes they are making in their health, these groups are ready to turn their walks into marches to make a difference.

"As you start walking, you start noticing 'oh we need a garden here' or 'this crosswalk is dangerous for our kids'," Dixon said. "And so, we are here to help women, to advocate for policy, to build infrastructure, to change their neighborhoods."

For Dixon, she feels empowered when she sees these women not only get healthy but also get active in their community.

"It feels great to have something practical I can do when I feel overwhelmed by the news." Dixon told CNN. "It feels great to have black women that I work with every single day to be my tribe. It feels amazing to go to a GirlTrek event and have women welcome me with open arms. So, I don't feel like I'm saving lives. I feel like they're saving my life."