Looking at Mark 13:24-25 we read this, “But in those days, after that tribulation, the sun will be darkened, and the moon will not give its light, and the stars will be falling from heaven, and the powers in the heavens will be shaken.”    Jesus is now talking about the days immediately preceding His return.  This prophesy is also repeated in Isaiah and also parallels what would happen when the 6th seal is broken in Revelation 6. 

“God has not destined us for wrath, but to obtain salvation through our Lord Jesus Christ, who died so that whether we are awake or asleep we might live with Him.  Therefore, encourage one another and build one another up.” (II Thess 5:9-10)    In other words, because we have such a great salvation in Jesus, we are to be a positive people, encouraging one another and building one another up with the truth of Jesus second coming.

The key word Jesus uses in Mark 13 when describing the days before His return is found in vs. 8, "birth pangs."   There are several ideas behind this phrase "birth pangs."  First it is a felt pain.  Any woman who has had a child will let you know that to have birth pangs is not a pleasant experience.