Derek Davis doesn't hesitate when I ask why he underwent life-changing surgery.
"I wasn't going to die wondering."
It is Friday afternoon and we are sitting in the kitchen of his Killiney home, talking about the incredible transformation in his health.
Two days later he would suffer a massive stroke. By Wednesday he would be dead.
It seems impossible to think that the man across from me that day, telling stories over tea and looking forward to boat trips and wearing chinos in the summer, would not live to see another week.
The interview was ostensibly about obesity, but in fact it was really a conversation about how much Derek wanted to live.
Just over a year ago, he had begun training to get fit enough for bariatric surgery. "At that stage I reckon I had two years left and I was reconciled with the fact that maybe I should just let things take their course. I had heard the chimes at midnight," he told me. "I had had a good life."
And then, a reason came along to give it another shot. "I became a granddad."
He takes out his mobile phone and begins looking through his photographs.
"He was three months premature," he says, without looking up from the screen. "He only weighed 2lbs and, to be honest, it was touch and go. . . he really wasn't expected to live."
Leaning across the counter, he shows me the source of his affection. "Look, he was tiny."
Aware of a looming deadline, I try to move the interview back to Derek's battle with his weight, but he isn't budging. "I just want to show you when he was born. Like every proud grandfather I have thousands of pictures of my grandchild. You see, grandchildren make sense of it all. He is extremely winsome. The little fellow's default setting is happy."
It seems contagious. He calls the child "a scaldy little thing", and affectionately describes him in his first weeks as "a pathetic little bundle".
When I agree with how beautiful he is, he suddenly catches himself and brushes it off. "Ah you have to say that. . . all kids look like ET when they are born."
Still, his face looks as if it is staring straight into heaven.
Derek points to a picture on the wall of three little boys in a boat. "They are my three sons when they were little boys. They are off now. . . all grown up. There is a lot of rearing that goes into children, a lot of responsibilities. But you don't have any responsibilities when you get to see that," he smiles, showing me another picture, before telling me his plans for the summer.
Outside the house, a man is working on a boat. Derek, who talks about his love of boats, adds that the first thing he wanted to do after he lost weight was to go out and enjoy the water again, this time with his grandson. "Someone needs to teach this boy the important things in life. Like picking a decent bottle of claret and casting a fly," he says. "It was really his coming into the world that made me want to cling on a bit longer."
Looking back on his life, Derek describes the day a doctor told him he had diabetes and was slowly turning blind. In a lifetime of battling weight problems, he describes this as his lowest moment. "It wasn't a fear or a terror that I felt, but a melancholy. Particularly when the kids were so young. That I wasn't going to see them grow up. To me. . . that was shattering."
When I ask if his children ever confronted him about his weight, he tells me "love is blind" and recalls a story when one of his sons was teased in school. "The boy shouts at him 'Your daddy is fat' and my son replies 'Aye, but he's rich too'," he laughs.
His mood gets heavier as he explains the deeply complex and individualist nature of obesity. Doctors finally discovered Derek had a problem with his satiation gland since birth, which he says left him in a constant state of hunger.
The single most important piece of advice he had for people with obesity was: "Take control of your life, don't listen to anyone else, and you lose it because you want to lose it and it's your choice."
Derek credits his appearance on Brendan O'Connor's Saturday Night Show as a turning point in his battle with obesity. "[Obesity expert] Donal O'Shea had nearly 300 patients on the waiting list for bariatric surgery. He had applied for funding. And after a prolonged campaign - including Brendan O'Connor's programme - (the HSE) agreed to fund 50. But that means there are around 250 more at serious risk."
Derek says he appeared on the show and is speaking to me today because he feels "a moral debt" to 'heroes' like Dr Donal O'Shea who "kept me alive for 20 years".
On the day he collapsed, he continued to speak out about the obesity epidemic, appearing on RTE's Marian Finucane Show with Aine Lawlor.
Listening back I can hear the same raw emotion in his voice when a fellow panellist uses the word "fat" in a sharp tone that Derek says upset him as a child.
During our interview he had spoken about the need to end the stigma surrounding obesity and the need to stop fat-shaming those affected by it. "There is a line in Romeo and Juliet," he told me. "When Romeo is laughing at one of his friends who is love-sick and his pal replies: 'He jests at scars, who has not felt the wound'."
Before I go, I ask Derek if being thin makes him happy? He pauses for a second. "It sounds trite. But the thought that I might be around long enough to get to know my grandson. . . ," he says smiling. "That is a great source of joy to me."
Then he adds: "But, do you know what? You're only in with a shout. Nobody has any guarantees. There are people, much younger than me, dropping dead every day."
Derek, appearing very much a man at peace with himself, adds he has changed in another significant way. "You know what's missing? The guilt," he says. "The guilt is now gone."
He knocks his knuckles on the kitchen table, drumming out the words for emphasis: "I have done whatever I possibly can. . . I can't do anymore."
As I walk out the door, I thank Derek for giving me his time at such short notice. He calls out after me: "No problem at all. Just do your bit now and get the message out."