David Burston was making grand plans when he received a stage 4 cancer diagnosis late last year.

The 72-year-old from Cairns had just bought an old yacht, aptly named Tropical Dream, to fix up and sail around Australia.

There were few signs he was ill. He started needing to pee during the night and developed a slight limp, which he put down to a muscle strain.

"The last thing I would have said is, 'Oh, I've probably got cancer,'" David said.

But several anxious weeks after a suspect blood test, a PET scan confirmed he had prostate cancer, which had also spread to some bones and lymph nodes.

David said doctors were "slippery" when he asked for a prognosis, but eventually gave him a ballpark of around two to 10 years likely left to live.

So, he set about "getting his affairs in order", such as updating his will and completing an end-of-life healthcare plan.

But he was not ready to give up on his sailing dreams just yet.

"I said, 'No way, I'm jumping on that boat,'" he said.

David is pressing ahead with fixing up Tropical Dream in the hope of setting off around Australia mid-next year, as long as his health allows.

He has so far responded well to radiation and hormone therapy, which have shrunk some of his cancers, although the medication has given him "male menopause".

"I break into sweats, but it was so effective I'll happily put up with that," he said.

But David is well aware that his plans can only be so solid.

"With these diseases, you're never out of the woods. This can come back and belt me," he said.

Hope in the face of death

People who are approaching the end of their life can still make plans and look forward to things, according to Adelaide University professor of palliative medicine Greg Crawford.

"That's the nature of the human spirit, I think. That you might know one thing, but we still want to have some hope," Professor Crawford said.

But he said doctors had a responsibility to help patients have realistic expectations, even though they did not have a "crystal ball" to predict exactly how someone's illness would progress.

Professor Crawford said a complete loss of hope and purpose was also a concern for the terminally ill, with a substantial minority experiencing depression or demoralisation beyond what would be considered normal sadness about dying.

'What you focus on grows'

Prostate cancer is generally one of the most survivable cancers, but it is considered incurable if detected late.

In Australia, about 36 per cent of patients live five years or more beyond a stage 4 diagnosis.

But David is heartened by the fact that treatments and survival rates have continuously improved over time, giving many like himself the chance of still having a "long life".

Whatever happens, he does not want to spend his remaining days paralysed by fear or allowing cancer to rule his life.

"It's not good, it's not bad, it is what it is," he said.

"I believe what you focus on grows."

It is why he prefers thinking about bilge pumps and one-inch valves for his boat rather than listening to people dwelling on their illness at cancer support group meetings.

"My religion is Bunnings [Warehouse], Saint Bunnings, and I go there and offer my alms on a very regular basis," he said.

David is still working, running a co-working space and selling industrial fabric shelters, and trying to improve his overall health by optimising his sleep and diet.

Now featuring prominently on his menu are things like turmeric, walnuts, black coffee and lots of sardines.

"After five days, you smell a little bit like you've been at the fish market all day," he said.

"I've got to help myself. I can't sit back and say the doctors have got to do everything."

The last adventure

While no solo sea voyage can be completely risk-free, David has tried to plan for as many contingencies as possible.

That includes "grandpa-ising" Tropical Dream to make it easier to handle as an older sailor with upgrades, including handrails and a rope cutter for propeller entanglements.

He also plans to keep tabs on his health with regular tests and telehealth appointments while at sea.

"And if something untoward happens, I can moor up in the marina and catch a plane back," he said.

But he is excited by the prospect of "magnificent sailing days", anchoring in places he has dreamed of visiting, and "meeting wonderful people".

He will just take things "day by day".

"If my body says yes, I'll do it. If it says no, I won't," he said.

And if his health and quality of life diminished to a point, David would consider voluntary assisted dying rather than "cling onto a life which is really not worth living".

"I see death as part of life. Everybody dies. It's just your last adventure," he said.