[hklgny]

For me he touches on this here:

“One thing that distinguishes the persistent is their energy. At the risk of putting too much weight on words, they persist rather than merely resisting. They keep trying things. Which means the persistent must also be imaginative. To keep trying things, you have to keep thinking of things to try.”

If you have ideas on what else to try, you persist. If not, maybe time to move on or risk it becoming obstinance.