"As we bounce back from the pandemic, it's important we lay the foundations for a country where everyone has the opportunity to succeed, with our younger generations front and centre of this mission", Johnson said in a statement.
He said the coronavirus had been a "disaster" and an "absolute nightmare for the country".
The rebuilding programme will start in 2020-2021 with the first 50 projects and will be supported by more than one billion pounds ($1.23bn) in funding, the government said.
Mr Johnson said an economic effort like the one seen in the USA under President Franklin D Roosevelt as it dealt with the Great Depression in the 1930s was needed for the UK.
"On the bill for all of that: this is the time to invest".
He used a 2004 Daily Telegraph column to say that it was people's "own fat fault" if they were obese and "the more the state tries to take responsibility for the problem, the less soluble the problem will become".
"But in the end what you can't do at this moment is go back to what people called austerity, it wasn't actually austerity but people called it austerity, and I think that would be a mistake".
"This is the moment for a Rooseveltian approach to the United Kingdom".
Mr Johnson said reports of him looking wraithlike were complete nonsense.
Asked whether he thought every day about the high level of total virus deaths and infection rates in Britain, Johnson said: "Every day".
"Local hospital admissions are coming down, so are the death numbers".
"I totally understand that and we will". I happen to think that the moment is not right now. when everybody is flat out, I don't think the moment is right now for consecrating a huge amount of official time to all of that.
Johnson, who in his youth was slender, has ditched takeaways since his illness and even told meetings that "it's all right for you thinnies" when discussing the novel coronavirus, British media reported.
"Had there been work on this from the day the schools closed down, I genuinely think we could have had all our children back in school by now, but the Government was asleep at the wheel, didn't get to this until too late in the day, and now we're in the situation where children will be able to do other things this weekend, but not be in school on Monday".