David's overarching trust in God's plans is nothing short of incredible. On two separate occasions, David had the opportunity to end Saul's life, but he chose not to do so. Honestly, no one would have blamed David if he had followed through with this. In fact, his men were a little ticked off that he didn't do what any other person would have done. After all, what more vulnerable position could a king be in than when he is relieving himself? David understood something very important: that God holds the future. That meant he didn't have to fight his way to get the very thing that God had promised. It would (and it eventually did) work out the way God ordained without David's "help" in speeding the process along.
There are a lot of lessons we can learn from this, and the biggest one for me is that I don't need to fight on God's behalf. His plans will come to fruition without me forcing them into place. Such a mindset can be relieving because I learn that it doesn't depend on me. Is God asking you to trust Him with something? You will never need to take a shortcut for Him… He will work things out in His time because He is the One who holds the future.