I have been reading D. Peter Burrows' book JONAH, the reluctant missionary (Gracewing, 2008) in which he explores the book of Jonah, but does so by offering a wide range of Biblical links. He links the story to many other parts of the Bible in a fascinating way.
I was particularly struck by a little comment about Moses in which he uses what happened to Moses, when he was called and empowered to do God's work, as a definition of a sacrament. He is pointing out that what matters is the difference that God makes.
Thus, he writes (p. 103/4) - "This reliance upon God rather than upon self is called 'faith' and Moses has no signs of power - he is a weakling. God clearly likes this about Moses and says in effect: 'You supply the staff, your right arm and a little water; I will add the power.' The staff becomes a serpent, the right arm becomes leprous and the water turns to blood. Moses supplies the little things of his life; God adds the power. What better definition of a Christian sacrament? 'You bring what you have and offer it to me; I will add the power of heaven.'"
God doesn't need our strength, just our weakness.