In the very beginning God created us in His image. Part of that image, I believe, is the ability to attain holiness. Even though our holiness is attained though the shed blood of Jesus, we must still live a lifestyle which reflects that holiness. And we can do this if the goal (heaven) means more to us than anything else this life has to offer.
The KJV says: ". . . gird up the loins of your mind" we must prepare our minds daily for the things we will encounter.
There are many things that can intoxicate our minds and render us useless in serving God. Such things as pride, arrogance, greed, revenge, hate, laziness, the lure of drugs, etc. We should be on guard against those things which would weaken our resolve to be faithful, take our minds off the goal or convince us that there is some better or easier way.
We need strong, complete and never failing hope. We need to abandon old habits that hinder or progress as Christians, to be holy.
Edit:
Other thoughts about this verse??
I heard something interesting from my Bible professor. "Gird up your loins" refers to something that Israelite men in ancient times did. As you all are probably aware, men in ancient Israel wore robes, which of course had what were basically skirts. The skirts were split along the sides so that they could tie up the skirts when they needed to run. This action was referred to as "girding up one's loins", since the strips making up the skirt were called loins. Essentially, I think God is saying to prepare our minds not only for temptation, but for learning as well.
