He doesn't, can't, take his eyes off it for a split second.

There's no feeling in his hands - or indeed his feet - so, if he's not careful, the steaming coffee could well end up all over his lap.

"I actually just have to retrain my brain," Mr Irvin said.

"I'm very much used to sitting around, holding a glass of wine, having eye contact and chatting with people.

"And I find myself looking down and going, 'Why is the wine all over the table?' because I can't feel the wine glass.

"Even with my phone, I'll hold it up to my ear and wonder why people have stopped talking to me and the phone's on the ground because I didn't feel it fall out of my hand."

So severe is the nerve damage wreaked by intense chemotherapy, Mr Irvin can only write one thing after a month of concerted practice: his name.

The Bega Cheese chairman has only been back at work for a couple of weeks after an eight-month absence to face an aggressive bowel cancer.

He chose familiar territory for the interview, the panoramic meeting room of long-standing advisors Kidder Williams perched 48 floors above Melbourne's CBD.

The setting and the coffee cup somehow symbolised just how much everything had changed and yet remained the same.

Not being able to write, for instance, required some real adjustments for a man who liked to compile his thoughts in neat cursive.

"I was surprised at how tired I was at the end of each day," Mr Irvin said.

"Obviously, there's that extra mental strain and that additional thing of realising, 'Well, you have to start to do things differently'.

"Even right down to when people would give me a document in a meeting, I'd write all over it.

"Now, I look at it and think, 'Right, I need to find a way to get my thoughts on that'."

Laughing, he recounted asking someone at his most recent meeting to write notes for him.

"I'm not upset about it in any way, it's just a fact of life and it'll either come back and improve, or I'll just sort of retrain and approach some of those tasks that I used to do in a different way," he said.

The cancer ordeal also changed Mr Irvin's approach to his health.

"I was that terrible, stereotypical male that worried about work, and worried about family and social life, and didn't worry about my health," he said.

"I kept going, 'Look at me, I'm healthy and I never get sick, I never take sick days.'.

"So, when my wife would suggest that I go and get a checkup or even work would suggest that I might need to, I would say, 'Yes, I will,' but I never would.

"It wasn't that I had any great objection to it, I just never bothered to make the time.

"And so, the big thing that I reflect on firstly is, you know, I say to everybody, 'Don't be a stupid male,' because it seems to be particularly males that don't look after their own health.

"The consequence for me was I went from wandering in, saying, 'I feel a bit tired,' to five days later having major surgery, and then having to recover from that as rapidly as I could so they could start very intensive chemo."

He'd also had, Mr Irvin admitted, a big dose of denial.

"I remember my oncologist said to me, 'You will need six months of intensive chemo,' and my response to it was, 'Well, that actually doesn't suit me very well, you know, and I am surprisingly resilient. And I'm actually quite fit. And I'm a dairy farmer. So I reckon you could give me twice as much in half the time.'

"'Couldn't we just do it in three months and you just give me twice as much more quickly?'

"She said, 'You don't understand Barry, I'm going to take you to the edge of death each time I give you a round of this chemo.

'If I give you twice as much, I kill you'."

Mr Irvin's schedule hadn't ever allowed for illness.

He had worked "never less than 60, more like 80 hours most weeks and sometimes a bit more".

Being chairman of dairy processor Bega Cheese, which turns over more than $1.4 billion, is a big enough job but it wasn't Barry Irvin's only job.

The father of a reliant autistic adult, Matthew, Mr Irvin is also the very committed chairman of the Giant Steps charity, which supports children and young people with autism.

And he's a dairy farmer who religiously milked his cows on Monday mornings.

"I've always had this thing that your memory does fade and there's a sense of reminding yourself every day what all your suppliers are doing and what they're going through," Mr Irvin said.

"If you're dealing with drought, they're dealing with drought and dealing with floods and mud and whatever it might be, quality problems or whatever else.

"It can fade if you don't keep doing it and reminding yourself where this business began, so I always just had the philosophy that I wanted to do that.

"I would always start my week like that, which would mean a very early start.

"And then I would work, obviously, all of the hours it took to to get what we needed to achieve at Bega Cheese.

"And then, if I had other time, it was always dedicated to Giant Steps."

The cancer and its gruelling treatment forced Mr Irvin to withdraw from all of that.

"It took everything I had, it took every piece of willpower and every piece of resilience and every piece of energy I could muster," he said.

"In that true dairy farmer-fashion - where you're as sick as a dog and you've got to get up and milk the cows - every morning, I would be as sick as a dog and I would've had one or two hours sleep through the night if I was lucky and I'd been sick several times a night, but I would go, 'I'm getting up and I'm walking or I'm lifting weights,' because that was something they wanted me to do.

"And I would sit there in front of food and want to throw up but force it down.

"All that stood me in pretty good stead.

"Interestingly, psychologically, it caused me to reflect but it didn't take away my optimism.

"I can honestly say I don't think I ever felt sad; to me it was another task."

In the depths of his illness, Mr Irvin did consider whether he would return to work but realised chats with colleagues about big-picture food, business and agriculture topics seemed to enliven him.

Asked what the ideal work-life balance would look like once he was fully recovered, he chuckled.

"This answer will drive my wife crazy," Mr Irvin said.

"But the truth is, I knew when I'd made the decision to come back that you can't half do this job - you're either doing it or you're not - and that includes my personality.

"Even if I wrote it on a blackboard and promised myself that I would only travel once a week or something, I know myself well enough to know that as soon as I'm well, I'll forget about all that and I'll go back to doing what I'm doing.

"Interestingly, I've only been back for a couple of weeks and, so far, we failed to keep me in one place for any more than three or four days, so I've started being very much in the routine that I had before."

Still, Mr Irvin is willing to make perhaps one concession.

His son, Andrew, has assumed management of the dairy farm and Barry has announced he will forgo the regular Monday morning milking to become the 'relief milker'.

"The truth is - especially, I guess, given the challenges the industry's got - I just think that I have to be able to give it my all," Mr Irvin said.

"The thing I will make sure I do is that, if I feel myself being exhausted and I feel my health fading, I will make sure that I do look after myself a little better."