Whatever happens, I have the power to think about it correctly. If I can do this, why am I upset? Things beyond my understanding don't affect my mind at all. My thoughts are the only thing that truly concerns me. Keep this in mind, and you'll be fine.
It is in my power concerning this thing that is happened, what soever it be, to conceit that which is right and true. If it be, why then am I troubled? Those things that are without my understanding, are nothing to it at all: and that is it only, which doth properly concern me. Be always in this mind, and thou wilt be right.