I can't tell you to appreciate what you have. You've never been without it, how would you ever be able to understand its value?
I can't tell you that it's possible to miss something you've never had. There's nothing you've never had that hurts so much it's like a hole in your heart. You've never been nostalgic for places you've never been, and you've never missed people you've never known.
You will never understand, and that is your tragedy. But I can't know what it's like not to understand, and that is mine.