The prime minister has described the easing of lockdown restrictions in England on Saturday as the "biggest step yet on the road to recovery".
He urged people to act "safely" as many businesses - including restaurants, hairdressers and cinemas - reopen.
But the PM warned that "we are not out of the woods yet", adding he would "not hesitate" to reimpose restrictions if there were spikes in Covid-19 cases.
Most of the latest easing measures will come into force at 00:01 BST.
However, pubs must wait until 06:00 BST as a "precaution" to avoid midnight parties.
"The success of these businesses, the livelihoods of those who rely on them and ultimately the economic health of the whole country is dependent on every single one of us acting responsibly," Boris Johnson told a Downing Street briefing.
"We must not let them down."
Mr Johnson said he wanted people to "enjoy summer safely".
Pub-goers are being encouraged to book tables in advance, while live gigs and standing at the bar will not be allowed.
The prime minister also said government strategy would move from "blanket national measures" to "targeted local measures".
He added "good progress" was being made regarding the reopening of other business, such as nail salons and night clubs, and that a timetable will be set out next week.
Outbreaks of coronavirus are inevitable.
The virus is now at much lower levels, but it has not gone away and may never go away. Until we have a vaccine it will always pose a threat.
We have already seen outbreaks in Leicester, Weston-super-Mare and Kirklees. Relaxing lockdown will make them more common.
Remember, this is a virus that thrives on close contact - the more people we come into contact with, the more coronavirus will spread. It was true in March, when lockdown came in, and it is true now.
However, outbreaks are not a massive problem as long as they can be contained.
If they can be spotted and rapidly stopped then an outbreak may cause local disruption, but not "National Lockdown Two". This will be the challenge for NHS test and trace.
However, some scientists are concerned lockdown is being lifted too quickly and that we are not yet able to stay on top of the virus.
The danger is failing to stop an outbreak could lead to coronavirus spreading widely and cases surging.