"If it is not right do not do it; if it is not true, do not say it"-Marcus Aurelius. This quote shows me that If I know that what I am doing is wrong, then I shouldn't do it at all. Or if I'm saying something that isn't true, then I should shut my mouth.  For example if I try to do drugs and spread false rumors to my peers and i know it's wrong, then i should stop immediately.