New Zealand was doing well compared to comparable countries, and the challenge would be to sustain that growth and make sure all New Zealanders benefitted from it.
He downplayed the prospect of immigration taking centre-stage in the election campaign, despite new data showing another record net gain in migrants in the past year. Forecasted slowdowns in migrants would mean immigration would not be a major issue, he said.
Labour leader Andrew Little, on the other hand, said the election would be fought on housing affordability, access to healthcare and quality education, safer communities and a stronger economy.
"Only by changing the Government can we do that," he said.
"We're well prepared, our teams are in place, our plans are well advanced and we'll be working hard to convince New Zealanders we can help give them a fair shot at the Kiwi Dream."
WATCH: Barry Soper analyses Bill English's election announcement
English said National would be "taking nothing for granted" because MMP elections were always close.
His party would continue to work with Act, United Future and the Maori Party in any post-election deals.
New Zealand First was "unlikely partner" because of its protectionist views, English said, but he was open to negotiations "depending on the makeup of Parliament".
He ruled out working with Labour or the Greens, saying they were "increasingly far-left and inward looking".
During his press conference, he repeatedly attacked the two parties, accusing them of campaigning on a "vibe" and of having no policy or belief in New Zealanders.
Green Party co-leader James Shaw said his party was more prepared than any previous election.
His party's platform would be ending child poverty, affordable housing, clean rivers and lakes, and a fairer economy.
The Greens "offered a credible, compassionate, progressive alternative" to National, Shaw said.
The election date was chosen because it was almost exactly three years after the 2014 election, on September 20.
It also allowed the Prime Minister to attend two global forums - the East-Asia summit and Asia-Pacific Economic Coordination (APEC).
Another unmentioned factor is that it falls between All Black tests on September 16 and September 30.
English will expand on the Government's agenda in a State of the Nation speech in Auckland today.
The speech will include new policy, and will also cover English's personal background and what drives his political beliefs.
KEY DATES
August 17 - last day of Parliament
September 6 - overseas voting starts
September 11 - advance voting starts
September 23 - general election
