Rem actam agis seems to me a reasonable motto. It comes from Plautus’ Pseudolus and is pronounced rehm AHK-tahm AH-ghis. It means, “You are doing something (that has already been) done.” Most of us are, most of the time. I know I am. So, even though most of what most of us are doing is hardly original or even interesting to anyone but ourselves, I think the trick is to not worry too much about it.