David is called a man after God's heart. This can be a little confusing when you get into his story, because he's guilty of adultery and murder and cover-up. He's a train wreck as a husband, and he's worse as a dad. But his heart belongs to God. His whole life is immersed in the presence and story of God. What lights him up is to serve God and love God, and when he mess up—and he does—he repents and wants to get right with God again.
Even you can’t tell yourself how to change, because you didn’t create you. To love someone is to desire and work toward their becoming the best version of themselves. The one person in all the universe who can do this perfectly for you is God. He has no other agenda. He has no unmet needs he is hoping you can help him with. And he knows what the best version of you looks like. He delighted in the idea of it, and he is already working on it. The apostle Paul said, “We know that in all things God works for the good of those who love him.” Which means God is at work every moment to help you become his best version of you.
The greatest moment of your life is now. Not because it's pleasant or happy or easy, but because this moment is the only moment you've got. Every past moment is irretrievably gone. It's never coming back. If you live there, you lose your life. And the future is always out there somewhere. You can spend an eternity waiting for tomorrow, or worrying about tomorrow. If you live there, you likewise will lose your life. This moment is God's irreplaceable gift to you.