Looking at this verse in the KJV, you might think these are the same Greek words translated commonly as "watch ye", "therefore", "pray" or "worthy". Yet, none of those words appear here. Many unique words do appear and their meanings are much more complicated than the KJV translation.

"Watch ye" is an uncommon word, used only in one other verse, that means "to lie awake", "to pass sleepless night," and "to suffer from insomnia." "Stay awake.

The Greek word translated as "therefore" means "but", "however", and "on the other hand". Since it always falls in the second position, translating it as "however" often captures its feeling better.  It is edited out like this when the KJV translators see no contradiction to a previous statement. It is likely that Jesus is contradicting something that is said to him.

There is no "and" in the Greek. The next verb is not active. 

"Pray" is another uncommon word that means to "lack", "miss", "stand in need of", "want",  "to be in want or need", "require", and to "beg a thing from".   It doesn't mean "pray" though the sense of "needing" at thing can mean "begging" a thing. However, here there is no object of this need. The form is that of an adjective, describing the person addressed, where they are needing or lacking themselves.

"Always" is from a phrase of three Greek words that mean "in all seasons".  This phrase appears before the "needing" verb and after the don't sleep. This first line is a bit of a joke: "don't sleep in all seasons." This seems to be a light-hearted response to a question about when they can rest. The word translated as "in" also means "within", "with," or "among." The word translated as "al-" is the Greek adjective meaning "all", "the whole", "every," and similar ideas. "Seasons" is a noun that means "due measure", "season", "opportunity", "time," and "profit."

The word translated as "that" is an adverb or a conjunction that starts a subordinate clause "there", "where," and "in order that."

"You may be accounted worthy" is a verb that Jesus only uses here. It  means to " overpower", "prevail over", and "have the upper hand." It has nothing to do with worthiness, as Jesus uses the term. This idea is completely lost in translation.

"To escape" is another unique word that means to " flee out or away", "escape", and "to be beyond".  The literal meaning  is "to flee beyond". The root word that means "flee" is one that Jesus commonly uses.

The word translated as "all" is the Greek adjective meaning "all", "the whole", "every," and similar ideas. However, this adjective doesn't seem to modify "these things" as much as the following clause "that shall come to pass."

The "these things" is a pronoun that can mean "this" or "that," the nearer or the further depending on usage. The "things" comes from the neutral, plural form.

The word translated as "that " is the Greek definite article, which usually precedes a noun and, without a noun, takes the meaning of "the one." The Greek article is much closer to our demonstrative pronouns ("this", "that", "these", "those"). See this article for more.  This is a very different word than then "that" above.

"Shall" is a Greek verb, which means "to be destined or likely to", "to be about to do something," or "to intend to" or "to have in mind to." It is in the form of a participle, uses as a noun, so " being destined." This is the way that Jesus uses this word, though it is not common.

The word translated as "come to pass," means "to become," and "to happen" for events,  that is, to enter into a new state. In Greek, especially as used by Jesus, it is the opposite of "being," which is existence in the current state. The meaning hear clearly applies to events so "to happen".

There is a disconnect here. The following phrase does not describe the events that happen but the people that are fleeing.

The Greek word translated as "and" is used as the conjunction "and", but it also is used to add emphasis ("also").  this does not join the following verb with the previous one, which was part of the description of events. It connects to the verb "to flee beyond".

"To stand" is from a common verb that means "to make to stand", "to stand", "to set up", "to bring to a standstill", "to check", "to appoint", "to establish", "to fix by agreement", "to be placed", "to be set", "to stand still", "to stand firm", "to set upright", "to erected", "to arise," and "to place."  It, however, is passive, so "be made to stand" or "to be established" or some other variations of it possible meanings.

The Greek word translated as "before" means "in front of" referring to place and when used to apply to time means "beforehand."

The phrase "the son of man" is the common way Christ refers to himself. It is discussed in detail in this article. Its sense is "the child of the man." The word translated as "son" more generally means "child" or "descendant". The Greek word for "of man" in the singular means "person" and "humanity" and "people" and "peoples" in the plural.