Kara Kennedy , 51, daughter of Ted Kennedy died as a result of many years of chemotherapy to tackle her lung cancer which led to her heart attack on Friday family members said.

The treatment weakened her entire system and she suffered the fatal heart attack while working out in Washington D.C.

Her death was first reported here on IrishCentral.com and then reported nationally in the major media.

"Her heart just gave out" said her brother, former Congressman Patrick Kennedy when speaking about his older sister, who was married with two children. She worked as a TV producer

Patrick Kennedy told A.P. that the cancer treatment “took quite a toll on her and weakened her physically.”

"She's with Dad now," he said

He said she loved to work out but “her heart gave out.”

Kennedy was described as a shy person who shunned the spotlight that so often shone on her father and relatives.

In an article that she wrote for The Boston Globe Magazine just last April she stated: “Unlike my father, I felt more comfortable behind the camera than in front of it. But like him, I found my greatest fulfillment in showing the needs and successes of others.”

In 2002, Ms. Kennedy was diagnosed with lung cancer but fought it successfully.

However it took a huge toll on he physically and is thought to have led to the heart attack.

Her ex-husband, Michael Allen, said Kara loved to work out at the health club every day.

"Insofar as I'm concerned her legacy is one of courage and grit and determination in the face of her own illness and in the face of many family tragedies and limitless, absolutely limitless, devotion to our children," he said.

Kara Kennedy was born in 1960as her father was campaigning for JFK in presidential race,

In his memoir Ted Kennedy wrote about his daughter" I had never seen a more beautiful baby, nor been happier in my life."

He also wrote in "True Compass" that she stayed strong even when diagnosed with lung cancer .

"Kara responded to my exhortations to have faith in herself," he wrote. "Today, nearly seven years later as I write this, Kara is a healthy, vibrant, active mother of two who is flourishing."

"Her magnificent strength in her successful battle with lung cancer was a quiet inspiration to all of us and provided her family and fellow patients with hope," the Edward M. Kennedy Institute said in a news release.

She loved her father too.

"What mattered to my father was not the scale of an accomplishment, but that we did our share to make the world better," she wrote. "That we learned we were part of something larger than ourselves."

The family was gathered at her home on Saturday and will release funeral plans later it is understood.

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