the last day of the world

There are people in the world who know that their every day can be the last. But living every day "like the last day" is exhausting. Therefore, they just live and enjoy with their loved ones, for this last day. Just like a day. If we seriously think about finding out that your day will be the last, it's terribly scary. Everyone says if they know that they have one day left to live, they would do what they really wanted, they would spend this whole day with family, with friends, with a loved man... And I have a question for this people. What prevents to do it now?