Each day, for 65 days, Tauranga woman Nikki Reynolds-Wilson and her older sister, Kristie Purton​ commit one random act of kindness. It's a pursuit made even more impressive as the sisters' time is limited and they'll spend almost half the year in hospital.

Nikki, 24, and Kristie, 33, ​have already surpassed their life expectancy – their parents were told the girls wouldn't make it past their teens.

The pair suffer from cystic fibrosis – a hereditary disease that fills their lungs with thick, sticky mucus, and it's affecting other organs, too.

SUPPLIED The sisters will spend almost half the year in hospital, because of cystic fibrosis disorder.

The condition is like having a cold that never goes away, Kristie​ explains. Instead, it grows worse, year after year. Eventually, their lungs will fail. Nikki​'s lung function is currently 20 per cent. Kristie​'s is slightly better at 30 per cent.

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SUPPLIED Nikki Reynolds-Wilson and Kristie Purton are performing a good deed everyday to raise awareness of their condition.

For more than a year, Nikki​ has been on a waiting list for a lung transplant. Her situation is made worse because of her size – she needs a child's lungs. She is resting in hospital on the day we talk to Kristie.

Transplants are a last resort, Kristie says. Doctors only put patients on the waiting list when they predict their lungs wll soon stop functioning, and they can be left waiting around for two years. But without a transplant, they will die.

Despite these exhausting conditions, the sisters have committed themselves to a 65-day quest to raise awareness of their condition in the lead up to cystic fibrosis awareness week on August 15.

SUPPLIED Each year, the sisters plan to do 65 good deeds across 65 days.

They've paid for meals at drive-thru, given grocery vouchers to random shoppers, and hidden scratchies in library books. They're baking cupcakes and giving them away on a crusade to brighten someone's day.

"We're literally just doing this to raise awareness," Kristie​ says.

In return for their gesture, all the sisters ask is that recipients look at their Facebook page, to try and begin to understand the genetic condition.

Kristie recalls a supermarket confrontation about a year ago, when an older woman told her she shouldn't be spreading her germs in such a public area.

"I tried to explain that you can't catch it, but she didn't have a bar of it. I was just thinking that if people knew what it was, they wouldn't judge you so much."