Unusual Prayer Tip

I was reading again in Spiritual Classics this morning and found this unusual prayer tip in an excerpt from The Cloud of Unknowing.

"...the best thing you can do when you start to pray, however long or short your time of prayer is to be, is to tell yourself, and mean it, that you are going to die at the end of your prayer. I am not joking when I tell you this: just think how impossible it is to tell yourself - or for anyone living to tell himself or herself - that you are certain of living longer than the time your prayer takes.
When you think of this, you will see that it is quite safe to tell yourself that you are going to die, and I davise you to do so. If you do, you will find that the combination of your general sense of your own unworthiness combined with this special feeling of how short a time you have left to make a firm purpose of amendment, will concentrate your mind wonderfully on a proper fear of the Lord."

I've been pondering this advice all day. It has to be the most unusual prayer advice I've ever read, and yet it is unusually refreshing. What does make us think that we will live beyond the next prayer. I wonder how my prayer would change if I was talking with God as though I were about to be standing with him? I wonder how that would effect what seems to matter to me now in my prayers?