What do you hear when you hear the expression "enough is enough?"
Some of you will hear frustration as it turns to resolution. You will hear "enough of this nonsense" or "enough of these excuses."
You might even hear Gandalf as he booms "Thou shalt not pass."
Some of you will hear a plea to be content, a statement that all the necessary criteria have been met. Enough is enough means that more is unnecessary. You can safely move in another direction, or even just drift. You have enough.
The two meanings meet on the line between motivation and frustration. Together, they imply that we have a set of criteria against which we judge experience, even when those criteria sit in the back of our minds. As soon as you say "enough is enough" you realize that you had the information you required to know what was acceptable, what was necessary, and what was extra.
Consider a situation in which you think those boundaries are unclear. Ask yourself, when would I know that "enough is enough?" You will find that you do know where the boundaries are, and what crossing them will mean.