Decision making

Is our ability to make judgments and focus a matter of willpower or is it like a muscle that can be exercised and strengthened? Could neither be the case? A new study suggests that our ability to make judgments is more chemistry than "strength."
What makes a patient chose not to undergo treatment, a decision that can reduce the risk of cancer by upwards to 30%? Facts or beliefs? (And another thing: Why do we pay so much attention to that homunculus jabbering away in our heads?)