Modesty once extinguished knows not how to return.

Certain inhibitions do not grow back once they are gone. The first time you do something you would previously have found unthinkable, the unthinkability is spent, and every subsequent time costs less. That is what makes the first crossing more significant than it feels at the moment, when it usually presents itself as an exception.

The useful question is not whether a single instance matters but whether you would be comfortable doing it routinely, because routinely is where it tends to end up. Where you have an inhibition you value, guard the first exception rather than the tenth. It is cheaper to hold a line than to rebuild one.