You will find rest from vain fancies if you perform every act in life as though it were your last. — Mediations, Book II

My Take – Anything you do might be the thing that makes your reputation.  Maybe it will be that the impression will be good, maybe it will be less than flattering.  The problem is that you never know.  The only way you can be sure is to do everything as if it was the one thing that everyone will remember forever.