He had long campaigned for the Voluntary Assisted Dying (VAD) bill to be passed in NSW, so that he could go out on his own terms. Instead, he died by suicide after he sent his family away to Sydney for a vacation.

"Due to the laws, if he had done it while we were around or had we been implicit in it, we could have faced jail time," his son, Bertie Daniel said.

"(Dad) always said he was disappointed that there were no laws for euthanasia in place.

"He kept saying that he had no quality of life and that if he was a dog he would have been put down years ago. I remember him always saying 'I wish my life was worth as much as a dog'."

Mr Daniel was just 15 years old when his father died. He said his childhood was "pretty usual" up until the diagnosis six years prior to that.

"We had to watch our dad, who was a very outdoorsy person and always liked to do his own stuff, degrade to the point where he couldn't do any of that any more," the now 21-year-old said.

"He was in constant pain. Often times he would cry himself to sleep. As a young child, when you're lying in bed and you can hear your parent sobbing into the night, somebody you look up to and admire, it is very distressing."

Mr Daniel found out about his father's death on the way back from the Sydney vacation.

While he was shocked at the news, he wasn't surprised.

"Finding out he had taken his own life, I completely understood," he said.

"While I hate the way he had to go out, I do understand completely why he did it and I think it was the best course of action given his condition. Given he was losing control of his hands, he wouldn't have been able to go out if he waited any longer."

A little more than five years after his father's death, Mr Daniel, who lives in Kanimbla Valley near Lithgow, in NSW's Central Tablelands took to the campaign trail himself.

"I just had this overwhelming feeling that I wanted to say something, that there were so many things that I wanted to say," he added.

"When I first started out campaigning, I was very sceptical that it would get through."

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He decided to write to nearly 40 members of parliament, telling them of his story.

While he only received half-a-dozen responses, this was the first time Mr Daniel truly believed the law may soon pass. To his delight, that moment came on May 19, when NSW became the last state in Australia to pass laws allowing people with a terminal illness to voluntarily end their own life.

"Absolute relief" was how Mr Daniel felt when news of the bill passing broke.

"I've spoken to people who have been campaigning for this for 40 years. I've been around when my father was campaigning for it and I've been working with groups for the past six or so months to try and get it through this time," he said.

"I felt proud that I'd managed to help out with finally getting the bill through and I knew that my dad would be very proud of me too."

The decision means within 18 months, people with a fatal diagnosis in NSW will be able to access voluntary assisted dying.

While Mr Daniel was delighted by the outcome, he couldn't help but wonder 'what if'.

"I always thought to myself, I wished that euthanasia was legal and we would have been able to be there for him when he died," he said.

"Now, people who are terminally ill with low qualities of life will be able to access assisted dying and be spared the suffering that they're dealing with. It's fantastic."

The bill passed the lower house of parliament after passing the upper house with amendments following a 12-hour debate.

It allows adults with a terminal diagnosis and up to six months to live to voluntarily end their life with assistance, with the approval of two independent doctors.

Independent MP for Murray Helen Dalton, who co-sponsored the bill, said it was important the safeguards did not disadvantage regional people.

"In small towns, it's hard enough to find one doctor, let alone two."