Without the bilateral transplant to deal with Mr Williams' cystic fibrosis 20 years ago, he would not have become a father to twin sons four years later.

Mr Williams co-founded Aussie Transplant Mates with heart transplant recipient Tim Lamberton, a social group for donors' families, recipients and people awaiting a life-saving donation.

They will join thousands of other Australians on Sunday in thanking organ and tissue donors, as well as the families who agreed to the donation.

Mr Williams has received two bilateral lung transplants; one in 1995, then a follow-up in 2008.

In 2000 he met the widow of his first donor and now keeps a photo album detailing his journey.

"[Before the transplant] I was alive, but I wasn't living; I was in a wheelchair, I was on oxygen," he said.

"A person donated their organs and not only saved my life, but gave me a second chance at life. And now I have two kids, and it's given them life, because they wouldn't be here otherwise."

Mr Lamberton had a Left Ventricular Assistance Device implanted in 2010, but received a heart a year later.

"I was connected to a heart pump for 18 months, so you can imagine going everywhere with a little bag of tricks, hooked up to lithium batteries, and there's a hose sticking out of your belly," he said.

"Then I received a heart and I was able to get some of my life back. I think this day will be a great day of significance for all doctors and carers. It's not just for recipients, it's all the others who are involved."

The DonateLife Thank You Day is part of a federal government push to increase rates of organ donation, as well as acceptance by families to agree to allow transplants to take place.

An Organ and Tissue Authority survey earlier this year found 81 per cent of donor families surveyed said the donation provided an opportunity for something positive to come out of a tragedy.