No time to waste

Rashi says G-d finished on shabbos his work a hair into Shabbat. This minute amount of work is permitted on Shabbat.

What is the lesson for us?
Every moment is important. If there is a moment that we can be doing our mission we should be doing it. If we don't the entire world is missing something and is incomplete.

In a similar fashion one can ask what is this last generation doing of benefit in this world after all the divine service of previous generations with their awesome accomplishments.

We have to know that it is specifically our small accomplishments that will conclude this grand enterprise of six thousand years and usher in the seventh day which is all Shabbat!

Likutei sichos vol. 5 pgs. 24-35