I procrastinate because of ADD. When something interests me, I have no problem getting started on it in a reasonable timeframe. If its boring, daunting, tedious, irrelevant, or unrewarding - no matter how high the stakes are, I will put it off until the last possible minute. In fact, my brain often won't cooperate until the last possible minute.
I don't consider it a spiritual issue in my life, but I believe it can be spiritual for some. Its a matter of discipline, and discipline is spiritual.