By Maariv in the Bracha of Hashkiveinu we ask Hashem, "V'Haser Satan Milfaneinu U'Mei Achoreinu", to remove the Yetzer Hara from in front of us and from behind us. What does this mean?
The seforim answer that when we want to do something good the Satan tells us there is no rush, start "tomorrow". Yet tomorrow never comes because there is always another tomorrow. But if we are ready, anxious, and willing to start immediately, the Satan employs a different strategy. He tells us it is too late. Had we done it yesterday it would have been great, but not anymore.
We ask Hashem to remove both these obstacles to our good deeds and self improvement. We ask Hashem to remove the Satan standing before us blocking us from taking action today. We also ask Hashem to remove the Satan from our rear-view mirror telling us to look back and see we missed our chance. This is the Kotzker saying, "It is always late but never too late".