Every year, I try to make a retreat at a nearby retreat house, and the same priest was there for a number of years. On Sunday morning, with the end of the retreat looming, he would invariably resort us to "finish strong". (He usually gave a sports analogy, which didn't go over well with the elderly women on retreat, but seemed to be a topic close to his heart.) However, his point was valid: even though the end was near, we couldn't just say, "Well, that's that. We are done." In fact, we needed to be just as vigilant and fervent in our last prayers as in our first.
This is a sound attitude for Advent as well. We aren't there yet, but we must press on, praying, hoping, anticpating and preparing. We "finish strong", and then can truly celebrate in the Light of Christ on Christmas Day.