When you get a chance, read 1 Samuel 17, (Yes, the whole entire passage). We glance over the story of David and Goliath without taking in the full accomplishment of David, but not just David, but of the God of Israel; the same God that you and I serve.
David killed a beast of a man with stone and sling because God favored him. God favored him because David trusted that the God of his yesterday, to be the same God today and he knew that he would be the same God forevermore.
God does extraordinary miraculous things in people who trust and believe that He is an extraordinary and miraculous God. David credited the Lord of Hosts as being all-powerful and would step down from eternity into his life. He knew God to be faithful! Do you trust him like that?
Father give me the strength, wisdom and your Spirit to be after your heart in that manner…