What might be the distinction between prayer and watching?
To me, Psalm 91 is an ideal prayer because it leads us into a place of refuge, where we can feel the safety, feel the presence of something very good, where we can trust God with our desires.
Watching, on the other hand, is more assertive, acknowledging a mental warfare going on "under the radar." This kind of assertive mental work is treacherous unless there is a moral foundation outside of the individual, in other words, unless the Divine Will is the goal.
To illustrate, I once took a class in Silva Mind Control, which promised great things for helping others through mental techniques. I was not disappointed, but eventually realized that these techniques could just as easily be used for evil purposes. Silva Mind Control, as most mental systems, is a method for getting what you want. This exposure made me aware of mental control techniques going on all around us, through advertising, organization self-perpetuation (AMA, RC, the Fed) etc. It made me feel very vulnerable.
It was about this time that I came across Science and Health with Key the Scriptures and found a rock to stand on in the realm of mental work. That rock is the premise from which we proceed, that God is Mind, my mind, and that I, as reflection, have only one will to satisfy, not my will, not my fellow being's, but the Divine Will. From this standpoint, the watching involves identifying those thoughts, or aggressive suggestions, that contradict the premise of one good God, and annihilating them with Truth. As an example, "my situation is hopeless" can be met with a statement from the Bible "I can of mine own self do nothing; the Father that dwelleth in me, He doeth the works." When our watching leads to a greater dependency upon God, we are building on a solid foundation.
However, when our watching consists of giving lip-service to God while willing our way to what we want, for example, "There is no power that can interfere with my desire because I know You would want that for me, and woe be to anything that gets in the way!" is the broad way which leads to destruction. The good this might seem to achieve will cover a "multitude of sins" and leave the individuals involved in a far more precarious position, subject to the will of the mental worker. This often happens in family situations where there is a strong, "protective," parental figure.
Many Christian churches warn against entering the mental realm, so-to-speak, and applying mental methods, because of the danger outlined above, but they overlook the fact that, whether we like it or not, mental manipulation is going on all the time. Best that we become aware of this, and learn to defend ourselves by subduing our own will, and cultivating a dependency upon the All-knowing, divine Love, to guide us.