DENIS Wright wasn't meant to live this long. He's had birthdays - 66 of them - but he's also had plenty of deathdays - the dates he thought he would "cark it".

"Every date we've estimated so far has been wrong ... I've embarrassed myself by staying alive," the historian from Armidale in country NSW told news.com.au.

Mr Wright doubted his two daughters and partner's son would see him marry Tracey, the woman who has loved and cared for him, after the "longest engagement in history".

But they did, in 2010, and he said he is "so emotionally close" to his wife "you couldn't separate us with cigarette paper".

Mr Wright has a death sentence named GBM 4 (glioblastoma multiforme). It's an extremely aggressive brain tumour that's been trying to kill him since December 2009.

Dr Charlie Teo, high-profile Australian neurosurgeon, has said the condition is "impossible" to cure.

Mr Wright doesn't know how much longer he has to live. His life is sustained by a drug called Avastin - but this time, he says, "there are no more arrows to fire".

Since his diagnosis, Mr Wright has written hundreds of posts on a blog, called My Unwelcome Stranger, about his experiences.

He writes about his troubled health, why he would rather call someone than send them a text (it's too slow to say anything other than "OK") and how he missed the true importance of a wedding (and that is "the receipt of as many and as expensive a range of gifts as possible," he joked).

Mr Wright wanted to share his life lessons, learned over his 66 years, with news.com.au readers. He provided 10 tips via email as his vocal cords have been significantly damaged by an increasing number of seizures.

UPDATE: READ HOW DENIS BECAME A SOUTH AMERICAN STAR

Life lessons by Denis Wright:

1. Don't spend your life in a job you hate. Life is too short to live it only in the evening and at weekends.

2. If there's something bad happening in your life you genuinely have no control over, learn all you can about it and how to live with it. Beating your head against a brick wall is unproductive.

3. If you think you can change it, then go all out to do so. Try to understand its nature and work with it where you can.

4. There are no 'good' and 'bad' decisions. If you made what you think might have been a poor choice in life, learn from it, and you might make a better one next time. You don't know what's going to turn out good or bad in the long run, so regrets are a waste of time.

5. Don't agonise about the past, in the sense that you can't change it. Live in the slice of time that's the now. You can't live in the moment; it's too short. The slice is richer. It contains a little of past, present and future.

6. Apologise as soon as you can when you think you've hurt someone. Don't try to pretend you're perfect. Accept responsibility where it's due.

7. Keep your options open for as long as possible. Don't close them unnecessarily.

8. Try to keep your sense of humour if you can, though it's not always possible.

9. Carpe Diem ... Or, for a change, seize the day!

And there's one more.

10. Do not be afraid of death. "If you're not more afraid of your own death than you need to be, then you need have little fear for anything life can hand out."

Mr Wright's blog, which has been visited more than 250,000 times by people from around the world, will be archived by the National Library of Australia online.

You can read the blog here.

Contact this reporter on Twitter @drpiotrowski @newscomauHQ | or email Daniel.Piotrowski@news.com.au