What is your line in stand?
The hill you’ll die on.
Your last straw.
It doesn’t (and shouldn’t) be as dramatic as any of the above, but knowing your threshold, your limit, is what it will help you when things go wrong.
When things are going bad, we enter into the “one more” syndrome – where incrementally “one more” thing will not hurt us until one day we wake up burnt out and overloaded.
Know your limit, know your threshold and beware of “one more”.