God will give us strength
Charles SpurgeonWhen we are called to serve or to suffer, we take an inventory of our strengths, and we discover that they are less than we thought, and less than we require. But our heart should not be lowered within us, since we have a word like this, on which we can lean, as it guarantees us everything we may need. God has an omnipotent force and He can communicate that force to us, and He promises that He will. He will be the food for our souls, and the health of our hearts; and thus, He will give us strength. You cannot know how much power God will put in a man. When divine strength comes, human weakness is no longer an obstacle.
Do we not remember times of work and trials in which we received such special strength that we were surprised by ourselves? In the midst of danger we remained calm, in the face of the loss of loved ones we were resigned, in the face of slander we had self-control, and in illness we were patients. The fact is that God provides unexpected strength when unusual trials come upon us. We rise above our weak constitutions. Cowards play the roles of men, fools receive wisdom, and the silent are given at the precise moment what to speak. My own weakness makes me cower, but God's promise makes me courageous. Lord, strengthen me "according to Your saying."
Source: The Bank of Faith Checkbook. Translation by Allan Roman.
http://www.spurgeon.com.mx/chequera/meditames/enero.pdf