You can never know everything, and part of what you know is always wrong. Perhaps even the most important part. A portion of wisdom lies in knowing that. A portion of courage lies in going on anyway.
In war, you say a prayer for your dead and ride on, because there is always another fight over the next horizon.
Your body is only clothing. Your flesh will wither, but you are your heart and mind, and they do not change except to grow stronger.