What is frustration

Frustration - keep trying to solve a puzzle with the pieces at hand, even if you've already established that some critical pieces are missing.

A couple of real world scenarios:

All these examples are different instances of the "fitting a square peg into a round hole" problem. The moment you realize that the task cannot be completed unless new pieces are added, stop and find those pieces. If you choose to play with the ones you already have, your only achievement will be yet another way to prove that "it cannot be done".