Addressing a Downing Street press briefing, the Prime Minister acknowledged that many people “anxious, weary and fed up”, but that the new measures were strictly time limited.
However, he promised that this lockdown was not a repeat of the last one.
He said the rules would end on December 2, but after that the country would return to the tiered approach.
“This is not a repeat of the spring,” he said.
“The advice I have received suggests that four weeks is enough for these measures to make a real impact,” he said.
“These rules will expire and on December 2 we plan to move back to a tiered approach. There is light at the end of the tunnel.
“These are difficult times. While it pains me to have to ask once again once again for so many to give up so much, I know we can get through this.”
The Prime Minister was also forced to defend the data used by his advisors to justify the lockdown, following criticism from the UK’s statistics watchdog.
He told the Downing Street press conference: “We try to make things as as clear as we as we possibly can.”
Mr Johnson acknowledged that the “projections vary widely” and there was also a “political judgment” to be made, taking into account the economic consequences.
“It’s very, very tough to make exactly the right call,” he said.
Mr Johnson said some of the facts were “irrefutable”, such as the number of deaths and people in hospital.
“I can’t quarrel with those data, we have to act on those data and collectively, that’s what we’re going to do,” he said.
Chief Executive of NHS England Sir Simon Stevens also attended the press conference.
He said that around 30,000 staff in the health service were either off with coronavirus or having to self-isolate, and “that has an impact”.
He added that that figure underlined the need to control the spread of coronavirus in order to protect the care that could be offered in the NHS
He said: “Our success in controlling community transmission of coronavirus also is a force multiplier, to what the NHS itself can then provide in the way of care.”