Up until yesterday, most people knew that they should take hygiene seriously, apply safe distancing, and stay home as much as possible.

After all, they had heard the Government say so time and again.

But for some, it still did not seem to have sunk in that Covid-19, which has infiltrated supermarkets, schools and malls, was starting to take root here in earnest.

People continued to leave their dirty plates, complete with scraps and bits of tissue paper, on the tables at hawker centres; and customers were seen crowding around wet-market stalls, ignoring the little red squares placed there to help them maintain some space between one another.

Not everyone was staying home when they could, and others continued to push the "no more than 10" limit when it came to gatherings.

People turned up at work sick, and went to bars for one last hurrah before the shutters came down.

New clusters formed.

More than 1,100 people are now infected, and five have died.

The news gets more alarming.

In recent days, the virus has surfaced - and is infecting a growing number of people, in a nursing home and in foreign worker dormitories - where many live together and numbers have the potential to explode.

Worse, unlinked cases - it is not known where or how these people caught the bug - have also been increasing. This signals that there could be other unidentified people in the community who have the virus and are spreading it, particularly as new evidence has surfaced that it can be passed on by people with no symptoms.

But when the Prime Minister speaks, people listen.

And yesterday, PM Lee Hsien Loong made clear he was worried.

"Looking at the trend, I am worried that unless we take further steps, things will gradually get worse, or another big cluster may push things over the edge," he said in a nationwide broadcast.

The next few weeks are critical, say experts, because the numbers during this period will determine if the healthcare system can cope, or whether it will be overwhelmed.

To prevent things from spiralling out of control, most workplaces will be closed, and most people will work from home.

Schools will do home-based learning full-time.

And for people going about their daily lives, they are asked to stay at home, as much as possible, to go out only if it is essential, and avoid socialising with others beyond their own household.

"The spirit of these measures is to get all of us to minimise physical contact. If we do not go out, if we avoid contact with others, then the virus will not be able to spread," said PM Lee.

"It is as simple as that."

So our everyday habits will have to change, although we can still go to the supermarket, get medicine, take a walk in the park, or even get a haircut.

And those who look on the brighter side say this is time for family, for reflection, and for some simpler living - a decluttering of life, at least for a while.

But everyone has to buy in, and to understand why such action is needed, because it could take just one person, acting irresponsibly, to derail the effort.

In its war against an invisible enemy, Singapore has done many things right.

The authorities have been transparent, acted swiftly as events unfolded, explained every new move put in place, and based their decisions on science.

Hopefully, individuals down the line now grasp the urgency of the situation and their critical role in defending the country against the virus.

Otherwise, there might well be more rules and restrictions, even a total lockdown, if infections and deaths spiral.

Hopefully, if everyone gets the message, we can avert that.