Always respond to every impulse to pray. I would make an absolute law of this – always obey such an impulse. Where does it come from? It is the work of the Holy Spirit; it is a part of the meaning of “Work out your salvation with fear and trembling, for it is God which worketh in you both to will and to do of his good pleasure” (Phil 2:12-13). This often leads to some of the most remarkable experiences in the life of the minister. So never resist it, never postpone it, never push it aside because you are busy. Give yourself to it, yield to it; and you will find not only that you have not been wasting time with respect to the matter with which you are dealing but that actually it has helped you greatly in that respect … Such a call to prayer must never be regarded as a distraction; always respond to it immediately, and thank God if it happens to you frequently.
– Martyn Lloyd-Jones –