"I asked the lady 'what does this mean?' but the expression on her face gave it away — her eyes were wide and she had a massive grin on her face," said the winner.
"When she told me I had won $19 million, it was like it didn't even register."
Like most Kiwi blokes, the winner prides himself on containing his emotions "so she probably thought I wasn't even excited — if only she knew how I was feeling inside, I was bursting with happiness."
He then started driving home.
"I thought I was doing a good job of holding it all together, but as soon as I started driving my mind began to spin. I just had all these thoughts rushing around."
To clear his head, the winner decided to go for a swim at Snells Beach.
"It was great, the water was cool and I swam out deep. All the rushing thoughts disappeared and I started to feel a lot calmer."
He then headed home to tell his partner the good news.
"While I was swimming I had been thinking about how I wanted to tell her, so I wandered in the house and casually asked her 'did you hear someone in Warkworth has won $19 million?'
"When she turned to look at me I said 'and you're looking at him'. She just stared at me in shock, trying to read my face," laughed the winner.
"When she realised I wasn't joking, we had a big hug and a kiss — it was a very special moment."
The $19.1 winner said he would now take his time thinking about what to spend the money on.
"I feel very fortunate to have won, but I want to let everything settle down a bit before I make any big decisions.
"It's actually quite funny I had a birthday a couple of months ago and when I blew out the candles on my cake I made a wish to win Powerball.
"Looks like the birthday gods are making wishes come true this year!"
Warkworth New World Lotto manager Tim Carmichael said his staff were left buzzing after the man came into check his winnings.
"The [staff] that were here on the night when he came in were just aboslutely buzzing and it's a fantastic thing to have happen.
"We're absolutely thrilled for the winner, as of course you would be, and it's just awesome, it's a really cool thing to happen for them and we're really stoked to have been the [store] that sold it to him."
He said it was the biggest prize the store had sold.
The Warkworth man was one of two tickets holders who shared the $38m jackpot prize.
The other $19.1 million Powerball winner was claimed by a Wairarapa syndicate of three generations yesterday.