Earlier this year Heidi Harty-Eugster was wondering how much longer she could last.

Now, she's planning to do the Christchurch Colour Run with her daughter and husband and it's all thanks to a family's selfless decision to agree to organ donation.

The 38-year-old Christchurch mother was born with Hypertrophic Obstructive Cardiomyopathy which meant parts of her heart became too thick and restricted its ability to pump blood effectively.

By the age of 17 she had undergone two open heart surgeries to cut away the abnormal growth.

Heidi Harty-Eugster, 38, needed a life-saving heart transplant. Photo / Supplied
Heidi Harty-Eugster, 38, needed a life-saving heart transplant. Photo / Supplied

Then, at 25 she went into cardiac arrest outside the hospital while cycling to work one morning. A taxi driver found her and got help.

She spent two days in a coma and had a defibrillator implanted in her to correct abnormal rhythms. The defibrillator saved her life a number of times since.

At 33 she had a third open heart surgery to repair a leaking valve but that caused other issues and a year ago she was told the only option was a transplant.

Doctors told her there was a 50 per cent chance she would be dead in two years.

By December last year Harty-Eugster couldn't walk 50 metres without stopping to rest. She had to stop working and could only manage one activity a day. She got breathless just talking or eating.

"In the last weeks I just didn't know how much longer I could go," she said.

Heidi listens to her old heart for the last time. Photo / Supplied
Heidi listens to her old heart for the last time. Photo / Supplied

While waiting for a new heart she had two false alarms - the first time it went to someone sicker and the second time it turned out the heart was not viable.

A few months ago she got the third call and knew it was her day.

"I already had my bags in the car. I just had a feeling."

The operation went well and she was up and walking a few days after.

"Taking a breath for the first time was just amazing because I hadn't been able to breathe like that for my whole life. I thought, 'if this is how normal people feel, I've been struggling my whole life without realising'."

Now Harty-Eugster can get out and about with her husband Chris and 10-year-old daughter Coco.

Heidi with daughter Coco, 10. Photo / Supplied
Heidi with daughter Coco, 10. Photo / Supplied

The family are planning to do the Taylor's Mistake walk this weekend to mark Thank You Day on Sunday - a day designed to show appreciation for organ and tissue donors and their families.

But for Harty-Eugster, every day was thank you day.

"I would not be here if it wasn't for a beautiful family saying yes to organ donation," she said. "Because of the donor, I'm now able to be a mother, a wife, a daughter and a friend."

But she was also aware of the flip side.

"I'm living and I'm going on to live a great life but there's a family out there that's on the complete opposite spectrum where they're grieving the huge loss of a family member. It's pretty amazing to think that someone made such a selfless decision to save a life.

"All donors and their families are really heroes in my opinion."

Last year, organs were donated by the families of 73 people who had died in New Zealand allowing 215 people to have life-saving organ transplants. Of those, 24 were hearts, 20 were lungs, 52 were livers and 118 were kidneys.

Each donor has the potential to transform the lives of 10 people through the donation of organs and tissue.

The number of donors has been steadily increasing since 2013 when there were only 36 deceased donors but more were needed.

Harty-Eugster said many people did not know it was not enough just to tick the box on your drivers licence because the decision came down to the families of those who had died.

She encouraged people to talk about it with their families so they knew what their wishes were.

Organ Donation New Zealand said families usually followed through with the wishes of their family member when they were known.

When there had been a prior family discussion about donation, making a decision at such a difficult time could be a little easier.

There are an average of 550 people waiting for transplants at any one time. The longest wait list was for kidneys.