In a statement outside Downing Street,an energetic Johnson praised the public for its"sheer grit and guts"in adhering to the lockdown but stressed the measures will remain in place for many more weeks.
The pandemic has killed nearly 21,000 people in Britain's hospitals,but the true toll will be much higher once the thousands of deaths in care homes and private houses are added to the tally.
However the rate of daily deaths is slowly falling,as are hospital admissions.
"If this virus were a physical assailant - an unexpected and invisible mugger,which I can tell you from personal experience it is - then this is the moment when we have to come together to wrestle it to the floor,"he said.
"And so it follows that this is the moment of opportunity,this is the moment we can press home our advantage,but it is also the moment of maximum risk. Because I know there will be many people looking now at our current success and beginning to wonder whether now is the time to go easy on those social distancing measures."
Johnson urged the public to be patient and warned the risk of a second spike was real.