Then all the tribes of Israel came to David at Hebron, and said, “Look, we are your bone and flesh. For some time, while Saul was king over us, it was you who led out Israel and brought it in. The LORD said to you: It is you who shall be shepherd of my people Israel, you who shall be ruler over Israel.” So all the elders of Israel came to the king at Hebron; and King David made a covenant with them at Hebron before the LORD, and they anointed David king over Israel. David was thirty years old when he began to reign, and he reigned forty years. At Hebron he reigned over Judah seven years and six months; and at Jerusalem he reigned over all Israel and Judah thirty-three years. The king and his men marched to Jerusalem against the Jebusites, the inhabitants of the land, who said to David, “You will not come in here, even the blind and the lame will turn you back”—thinking, “David cannot come in here.” Nevertheless David took the stronghold of Zion, which is now the city of David. David had said on that day, “Whoever would strike down the Jebusites, let him get up the water shaft to attack the lame and the blind, those whom David hates.” Therefore it is said, “The blind and the lame shall not come into the house.” David occupied the stronghold, and named it the city of David. David built the city all around from the Millo inward. And David became greater and greater, for the LORD, the God of hosts, was with him. King Hiram of Tyre sent messengers to David, along with cedar trees, and carpenters and masons who built David a house. David then perceived that the LORD had established him king over Israel, and that he had exalted his kingdom for the sake of his people Israel. (2 Samuel 5:1-12, NRSV)
“The LORD said to you: It is you who shall be shepherd of my people Israel, you who shall be ruler over Israel.”
The Lord said it so it shall be.
And you can take it from me, when the Lord says He wants something it is going to happen sooner or later, so we might as well go along with it and have it be done the easy way.
So the people of Israel understood, that God had said David was to be their king, and so they came together and anointed David as king.
So when God calls you, so you shall be.