Mr Weaver arrived in 2004 with big ideas on how to revitalise the club.
He tore up the old business model, building a slick bar on the ground floor of the stands, promoting the site's convention centre, and planning structures on unused green fields.
Some of his changes were initially unpopular, particularly with neighbours and traditionalists.
"When I was getting the job I told the board: 'Don't hire me if you want a race club secretary, because I want to fundamentally change who we are'," he said.
Mr Weaver knew he was the custodian of 155-year-old assets, but the business could not rely on betting to keep it afloat.
"If we were trying to run this as a racing business we would go bust."
Betting now accounts for less than 10 per cent of the racecourse's revenue.
There were only 26 race days in a year - so the club's assets had to also bring in revenue for the rest of the year.
Mr Weaver brought in Ellerslie's distinctive purple branding, targeted 25- to 35-year-old women, and engaged celebrity Bridgette O'Sullivan as the racecourse's ambassador.
He turned Ellerslie into a summer brand, focused on girls getting dressed up for a big day.
He said he had wanted to make the races like the excitement Auckland had felt during the America's Cup - without the risk of it being lost.
The changes have brought out the biggest crowds in 30 years - or as far as he can find records for.
"It's become fun again and got crowds back to the races."
He keeps in his office a large book from 2004 that outlined his vision at the time. Most of his projects have come to fruition.
"It's just starting to hit me now, but I have this so I can walk away and say, 'I've done that'," he said, with some sentiment. "It's time."
Though he is stepping away, Mr Weaver was clearly still attached, talking about what more could be done to turn racing into a proud export industry.
But for the past 18 months, he has effectively been working for two businesses.
His wife, Dr Libby Weaver (nee Ellis), is a leading nutrition specialist and weight loss expert with a burgeoning popularity.
Yesterday she was in Sydney giving a talk to 6000 people.
"I've never seen in my business career a brand that has more raving fans than people who have interacted with her," Mr Weaver said.
"Libby is unquestionably the talent in the business, but I've got to protect and leave her in a space to write and create."
So Mr Weaver was taking over the business side of brand "Dr Libby", which he was confident could become a global phenomenon - like a Deepak Chopra for health.
He said the couple had worked out a smooth transition from being Mr Weaver and Dr Weaver - the businessman and guru - to Mr and Mrs Weaver, husband and wife.
"I'm going to walk from a CEO's salary and start on a sales rep's salary again. But I'm excited about it."
"The beauty of our commercial model is we can earn a dollar only if we can help someone."
But today, his focus will be on the Diamond Day races, where he has entered a horse he has a share in - with the hope of his first win at Ellerslie.
Mr Weaver said there was an overlooked beauty in racing, where punters could effectively enter their own sports team with a $1000 investment.
"One of my lasting memories will be the joy on the winner's faces and the thrill of the finish line," he said.
