Patricia Lauder bought a Fitbit to count her steps and help her lose weight.

But now, the 73-year-old credits the fitness tracker with saving her life. A few months ago, she wasn’t feeling well and thought her sinus infection may have turned into pneumonia.

“I went to the doctors to have that checked out and that turned out to be negative,” she told CBS News.

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Lauder then noticed her resting heart rate on her Fitbit was climbing higher and higher every day. One day, she experienced shortness of breath and her heart rate spiked to 140 beats per minute, so she called an ambulance right away.

She underwent a CT scan and doctors discovered a potentially life-threatening problem – two pulmonary embolisms, or blood clots clogging an artery in the lung.

“That showed a large clot in the lung artery in both sides,” said. Dr. JuYong Lee of UConn Health in Farmington, Connecticut. Lauder’s heart was also enlarged.

Lee explained that the blood clots in Lauder’s lung put strain on her heart, causing blood pressure and oxygen levels to drop to dangerous levels. Lauder received clot-busting drugs right away and the next day her clots were gone.

Without the help of her Fitbit, she says she might not be here to tell her story.

“It certainly helped me under the most recent circumstances,” she said.

Now Lauder says she’s counting her blessings – and back to counting her steps.