Consider a person who is in rather poor health. As Sickly is bemoaning his situation, a man appears to him in a vision and says that he has been sent to bring him health. Sickly is delighted to hear this and asks what he must do to receive health. The man says "believe in me". That sounds easy, so Sickly readily agrees. Before he leaves, Sickly asks the man's name and he replies "Exercise". The next morning Sickly awakes with the impression that he should walk a mile before breakfast. He brushes off the impression because he just needs to believe, to be healthy. This occurs every morning for a month after which "Exercise" appears again and asks how his health is. Sickly replies, "Just as poor as ever. Where's the health you promised to give me?" Exercise says, "Did you walk every morning as I put it in your mind to do?" Sickly replies, "No – you just said that I had to believe in you." Exercise replies sternly, "If you believe in me, you will do what I tell you to do."
Obedience to the Lord is not optional.