All individuals see life differently, and when it is all or nothing, it takes a heck of a lot of courage to stand up to cancer or any deadly situation and fight like heck to survive it. It is the most frightening reality you will ever experience as a human. It also takes just as much courage to accept defeat and let things run their course. Sullivan simply could not go that way. He did have to make that choice in his mind, soul, and body, silently begging for God's help through that moment.
It's something you face when you're at the pinnacle moment of going to the light or staying and fighting. He had been there, and he chose life.
As the pain became more intense and the light grew dim, he felt very weak and tired, But he somehow found the strength to begin the fight.