Being stubborn can be a good thing. Being stubborn can get you hurt. It's good when you are trying to crack something difficult, when others don't think it will work, when others give up. On the other hand, one can get in a rut, make no progress, or go so hard your body or mind, or immune system, breaks.
This is the line! I am standing at the edge of the precipice. I might fall or I might summit.