A storekeeper will sell to you on credit, to be paid for at a later date.  Why not do the same with spiritual goods? Do a few good deeds, or say a few Psalms or words of Torah, and let them be put aside and ready when you need them.  You will then be able to make use of this merit, and not be like one who must ask the storekeeper for credit. ~ R’ Nachman of Breslov zt”l