The Taoiseach Leo Varadkar has said the Government will not be afraid to re-introduce coronavirus restrictions if there is a second wave of the virus.
It comes after major changes to the plan for re-opening the economy, with most of normal life able to resume from June 29th.
Pubs, restaurants, gyms, cinemas, hairdressers and barbers will be among those allowed to re-open early.
Mass gatherings will be limited to 50 people indoors and 200 people outdoors - this will rise to 100 and 500 people, respectively in phase four.
People are being advised to still work from home if they can, while they should also wear coverings on public transport or where social distancing might not be possible.
Speaking on Friday, Mr Varadkar said: "Taking personal responsibility means not entering a place if you see it is packed.
"It means leaving somewhere, even if you are having a good time, if you have been there for too long.
"It means exercising judgement and self-control for your own sake, but also for the collective good.
"This re-phasing forward of the roadmap is made possible by the solidarity you have shown and the sacrifices, decisions and choices that you have made over the past few months suppressing the virus.
"Instead of being forced back, we have been able to push the spread of the virus back and advance forward.
"There is of course more work we need to do.
"We need to show the same determination and ambition in leading our economic recovery, creating new jobs, and getting people back to work and businesses open again."
He added: "In years to come we will never forget how the world was upended in 2020. Never again will we take something as simple as a haircut for granted, or time spent with parents or grandparents, or meeting friends for a drink.
"Thankfully we found ways to stay connected, even when we were forced apart.
COVID-19 is still having a major impact, but we have made enough progress to reopen Ireland in 4 phases rather than 5.
By working together we have saved lives & limited the impact of the disease. Thank you.
Here are the main things you should know about the weeks ahead: pic.twitter.com/49EZoGIY9i
— MerrionStreet.ie (@merrionstreet) June 19, 2020
"The mission of the next Government will be to repair all that has been damaged by this crisis. If we carry forward in the same spirit of solidarity, determination and hope then we have nothing to fear. Nothing is beyond us.
"Just as the Government will need, so too will we as citizens.
"We will need to continue to act responsibility, understand that we have no treatment or vaccine for this virus and until such time as we do, we will be living a different type of life. But a life where we can again do so many things that are important to us and our families."
And in an apparent reference to the 2004 film 'Mean Girls', Mr Varadkar said: "Some have asked whether there is a limit to what we can achieve. My answer is that the limit does not exist. We have been here before and we know the way out."
More information on phase three can be found here