We need the Holy Spirit to live in right relationships with God, ourselves and each other. Saul's story tells us where we end up in life when we desire what we want from our own understanding instead of trusting God's good will for us.
When we embrace the Holy Spirit, He fills us with love that we share with others like David did with Saul. When we reject the Holy Spirit, the Holy Spirit sends others filled with Him to rescue the lost one.
That's the good will and good heart of God for each one of us!