I will strengthen thee. (Isaiah 41:10)
When called to serve or to suffer, we take stock of our strength, and we find it to be less than we thought and less than we need. But let not our heart sink within us while we have such a word as this to fall back upon, for it guarantees us all that we can possibly need. God has strength omnipotent; that strength He can communicate to us; and His promise is that He will do so. He will be the food of our souls and the health of our hearts; and thus He will give us strength. There is no telling how much power God can put into a man. When divine strength comes, human weakness is no more a hindrance.
Do we not remember seasons of labor and trial in which we received such special strength that we wondered at ourselves? In the midst of danger we were calm, under bereavement we were resigned, in slander we were self-contained, and in sickness we were patient. The fact is that God gives unexpected strength when unusual trials come upon us, We rise out of our feeble selves. Cowards play the man, foolish ones have wisdom given them, and the silent receive in the self-same hour what they shall speak, My own weakness makes me shrink, but God’s promise makes me brave. Lord, strengthen me “according to thy word.”
C.H. Spurgeon, Faith’s Checkbook