Amazing Secrets of King David

The first mention of Davids name is in the book of 1 Samuel 16:13. The mention of his name was so significant because it came with an unusual gait. Before this time, he had remained an insignificant minor of the family of Jesse who, though young and underage, was saddled with a giant responsibility of taking care of the large flock of Jesses familyall alone in the wild field. He was left alone irrespective of various dangers that abound in the field. He was considered too young to be counted as one of the sons of Jesse even when Samuel the priest made a request to Jesse to parade all his sons for one to be anointed as the new king over Israel in place of the erring Saul.

But in 1 Samuel 16 verse 13, the story changed. David became a separated individual among the sons of Jesse with a clear distinction. Then Samuel took the horn of oil, and anointed him in the presence of his brethren, and the spirit of the Lord came upon David from that day forward (1 Sam. 16:13).
The significance of that unusual encounter became the separator and distinguishing factor between David and his brethren as events unfolded later in his life. That was because the Spirit of the Lord came upon David from that day forward.
David rose from an ordinary minor to an extraordinary warrior and a renowned king of all times. What are the amazing secrets behind this transformation?