To counter Clifford's argument that belief without sufficient evidence is always bad, I was inspired by a TV show about a character surviving cancer. Despite her not knowing for sure if she was going to get better or not, her belief in the success of her treatment as well as the positive thoughts from family actually helped her progress. In reality, doctors often say having a positive mind and a strong support system are the best weapons against disease (aside from medical procedures of course). It's reminiscent of the self-fulfilling prophecy, which is a prediction about something that ultimately becomes true, whether directly or not. Of course, this works by the fact that the confident belief in something unconsciously motivates behavior
