The man God uses, He chooses Himself. There is nobody (man or woman) in the Bible who has chosen him or herself to do exploits for God - because our righteousness is like filthy rags to God (Isa 64:6); our standards do not match up. Therefore He has to equip and empower us for victory. He does that so that no one can boast or take the glory due Him. "All glory, all majesty and power belong to Him alone".(Rev. 5:13)
We are taken by surprise when God chooses us, because we see ourselves as unfit for the task. But He takes our inadequacies, our shortcomings and our inabilities and works on them for His good purpose. Anyone who presents him or herself as 'well able' is doomed to fail.
32.000 or 10.000 fighting men could have easily defeated the Philistines and the Amelikites but 300 had a very slim chance. So when such a small number defeats a large army, there is no guessing that victory came as a result of God's mighty right hand.
God can work with a few as with many. No wonder He confirms that were 2 or 3 are gathered in His name to pray.