Insanity is doing the same thing over and over again and expecting different results.
- Albert Einstein
There is a fine line between perseverance and insanity. At what point have you tried your best, and it's time to do something different? It's a balance - a paradox. If you get in the habit of giving up as soon as something gets difficult, your life won't work, but if you keep tilting at windmills - madly trying the same thing again and again, your life also won't work.