(CNN) -- Anita Dunham's first heart attack started with a mysterious pain in her arm -- and, suddenly, the 34-year-old felt as if she couldn't breathe. After she got dressed, she could barely speak because the pain was so great in her arms and chest.
Jolen Johnson took this photo of co-workers wearing red Friday in Cedar Park, Texas.
Dunham, who had a second heart attack in 2002, wore red Friday to spread awareness about heart disease. Now 64 years old, she said she wants women everywhere to know that heart disease, the No. 1 killer for women, can affect women in all walks of life. She and others shared their stories with CNN's iReport.com. Read more about Dunham
The National Heart Lung and Blood Institute, part of the National Institutes of Health, promoted the red clothing day to spread the message that "Heart Disease Doesn't Care What You Wear -- It's the #1 Killer of Women," according to its Web site.
Others who wore red have family members who succumbed to heart disease. Robin Savage, 42, of San Juan Capistrano, California, said her grandfather, father and mother all had heart disease. Besides wearing red herself, she goes to heart events and takes pictures of them for a local Web site. 
See more from iReporters on National Wear Red Day »
Savage has to take beta blockers because her heart sometimes races when she eats certain things, particularly foods containing the preservative MSG. She watches her diet closely and exercises 30 minutes a day to keep herself healthy. iReport.com: Heart Disease runs in my family
For her sons, 9 and 12, she monitors their diet closely, but fears that she will die while they are young.
"It's such a huge void in your life, especially when you have your own kids and you don't have your mom around to, say, ask questions," she said. "I was completely lost when I had kids." Visit CNNhealth.com, your connection to better living
Peggy Roesch, a 24-year-old graphic designer from Cincinnati, Ohio, said her grandfather had a heart attack five years ago. She was recently inspired by her mother, who runs marathons, to start running more herself. iReport.com: Seeing red
Eileen Velez from West Palm Beach, Florida, has been organizing her co-workers to wear red to show heart awareness every year since 2007.
"If everyone is wearing red at the same time, somebody is going to notice," she said. iReport.com: Kimley-Horn and Associates
Despite the nationwide movement, Dunham said she hadn't noticed anyone else in her town of Earlimart, California, wearing red on Friday. Her message to others at risk for heart disease is to watch their weight.
"I tell [my daughter] every day, 'You know you need to start watching your diet or you're going to be in the hospital with a heart attack,'" she said.
CNN's Cristina Martin contributed to this report.
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