Is it a setback, or an opportunity to get better? Of course, know your limits. But know them because you found them, not because you invented them.
When it's difficult, when everything is failing and when you are sure you need to phone it in and give up. Don’t.
Use the side of your brain that is doubting and ready to give up as motivation to press on and find that limit. The funny thing is, you rarely find the limit because you’re capable of much, much more than you would ever believe. So press on and don’t give up.