One of the most difficult commands of Scripture to implement is that to "pray continually" (1 Thess. 5:17). It obviously doesn't mean every single moment of every single day, because then when would we do everything else? Or does it some sense mean just that? I can tell you that I have never met anyone who said that they prayed enough. Even Billy Graham says that the one regret he has about his life is that he did not pray enough. And so where does that leave you and me?
Elsewhere I've advocated walking prayers as a part of obeying this command, as a means of maintaining communication with God. Such prayers are not easier to maintain than devotional prayers, just different, but there is an advantage: I have not yet fallen asleep while walking and praying. But I'm after something else, a more continual awareness of God's presence with me and a longer conversation. Thus, interstitial prayer.
"Interstice," the root of "interstitial," is not one of those words most of us traffic in daily. I actually first heard it in law school, as a description of the silence of some otherwise seemingly comprehensive statutory framework addressing a certain problem. Or in constitutional law, the interstices in our Constitution were actually viewed by one Supreme Court as implicitly containing a general right of privacy (a la Roe v. Wade). An "interstice" is then a space between things or parts, especially a space between things closely set or, more to point, it is an interval of time. It is the in-between time --- the time when you flip with little real interest through the pages of a dog-eared magazine waiting for the doctor who is already behind, when you sit at a three-cycle traffic light watching what strange things people do in their cars while they wait (like brush their teeth), when your lunch date is 15 minutes late and you closely examine the floor, seating, and windows of the restaurant, realizing that it's not really very clean at all and wondering why a Grade A rating hangs on the wall --- all the times you are waiting for something to happen, soon. It is, if you will, one of life's parentheses. The question is how will you fill it?
"So whether you eat or drink or whatever you do, do it all for the glory of God," says Paul (1 Cor. 10:31), and that means the interstices of our day as well. This is terribly difficult if you think this means actual praying, at least in thought, at every moment. Our thoughts are fluid. We're not on task nor do we need to be 24-7. Rather, I like to think of interstitial prayer as remembering that Someone is with me, that even in silence there is present One who understands me and my day better than anyone and actually has the ability to help me, to give me what I really need. All I really want to do as a result of this realization is to continually ask God to help me remember that I am not alone. If I remember that, if I am cognizant during some of that valuable interstitial time --- time most people regard as a waste or fill with books on tape, music, or fantasies --- that God is with me, then I think the rest, the conversation, the dialogue, will take care of itself. Who knows? I may even come to wish for more time to waste with God each day, more interstices where I can remember and listen.