Mat 24:44 Therefore be you also ready: for in such an hour as you think not the Son of man comes.
Alternative 1: By this [wakefulness] you also become prepared: Because in the hour you don't expect, the son of man is on his way.
Alternative 2: Throughout this [time of pressure] you also become prepared: Because in the hour you don't expect, the son of man is on his way.
In this verse, Christ reemphasizes his earlier message of being awake and ready, saying plainly that we don't know wether or not he is on his way. He makes this point even more clearly in the next chapter, in Mat 25:13. He may also mean that we don't know what his coming means: our salvation or condemnation. A lot of the previous verses suggest strong that this change, like all changes, can be either good or bad.
Do you find it interesting that the only time previous to this that Christ uses the word translated as "ready" is to describe the readiness of the wedding feast in the parable of the king who invited the ungrateful guests in Mat 22:4 and again in Mat 22:8? When is this word used again after this verse? In the parable of the virgins who were "ready" and didn't fall asleep when waiting for the bridegroom in Mat 25:10. Like so many Greek words in Matthew, this word only appears when Christ's is speaking, not in the rest of the narrative.
Perhaps we should also say a little bit about Christ's use of the phrase "son of man." In the old testament, this phrase is used to refer to all of mankind, often with the idea of the descendants of the current generation. However, in Ezekiel, its use changes. It is the name that God or the messenger of God ("the one who spoke) uses to address Ezekiel.
Christ uses it to refer to himself and especially his power. His first use in Mat 8:20 where he says he has no place on earth. After that, he uses the term referring to his power to forgive sins and as the lord of the Sabbath. He defines "the son of man" as the one who sows the good seeds, with those seed being his word. The vast majority of his uses refer to the son of man's coming. It is the only term he uses when predicting his future betrayal, death, and resurrection.
Why does Christ use this term? There are probably a hundred reasons that I could discover it I just spent my time studying these specific verses and their connection (and if you look at them, a pattern does emerge), but my feeling is that Christ saw his story as the story of us all. The specific of his betrayal in Jerusalem aside, I think he is saying is that just like he is the heir to the prophets, we are all his heirs. The earth is not our home. We have the power to "let errors go," (translated as the foregiveness of sins) and to make our own Sabbath. We are all betrayed, die, and rise again. We all come to glory in our Father's house.
"Therefore" is from dia, which means "through" in space, "throughout" in time, "by this cause," "through," "thanks to," "by the aid of," "right through," and "to the end."
"Be" is from from gignomai (ginomai), which means "to become," "to come into being," "to be produced," and "to be."
"Prepared" is from hetoimos, which means "at hand," "ready," "prepared," "sure to come," "certain," "active," "zealous," and "bold."
"Think" is from dokeô (dokeo), which means "expect," "suppose," "imagine," "have an opinion," "seem," "seem good," and "to be reputed."
"Coming" is from erchomai, which means "to come" and "to go." It means "to set out" and "to arrive at." It is a little like we use the phrase "he is on his way,"or "to be under way," which can mean either that he is coming or going with no direct reference to the position of the speaker.