"I have seen [the] son of Jesse...who is skillful."  1 Sam 16:18 NKJV

KEEP PREPARING YOURSELF
 
David didn't suddenly become an expert marksman with a slingshot when Goliath showed up, or a master harpist when King Saul invited him to the palace. He took the long, slow, disciplined route. David had no idea what his future held, he simply found joy and fulfillment in discovering and developing his gifts.
 
Your greatest obstacle to personal growth isn't ignorance, it's the illusion of knowledge, it's in believing you've "arrived." When that happens you're done growing, which means - you're done! Which zone do you live it?

The Challenge Zone: "I attempt to do what I haven't done before."

The Comfort Zone: "I only do what I already know I can do."

The Coasting Zone: "I don't even do what I've done before."

Phillips Brooks said, "Sad is the day for any man when he becomes absolutely satisfied with the life he is living, the thoughts he is thinking, and the things he is doing; when there ceases to be forever beating at the doors of his soul a desire to do something larger which he seeks and knows he was meant and intended to do."

David's brothers knew his skills, yet none of them told King Saul about him. Be encouraged: you'll get there without them! "Then one of Saul's servants...said, 'Look, I have seen [the] son of Jesse...who is skillful in playing, a mighty man of valor."

David didn't compete with his brothers or complain about his status as a sheepherder. He just kept developing his relationship with God and sharpening his skills, and when the time was right, God promoted him. So keep preparing yourself.