I still remember a "Stanislavski moment" that occurred for me--surprised us all, and frightened my counterpart in the scene--during a college musical comedy, eons ago. Desperation was probably the trigger in that moment.
The ingenue who was due to come on stage didn't--and still didn't--and then, again, did not--and, for a moment, I crossed over and freaked out my counterpart with an appropriate--but scary--response that was escalating into new territory--until she finally came on--after a costume-change glitch had nearly rewritten the ending of that musical. It was an exhilarating experience--and too seldom achieved in my brief performing life.
So, sometimes the moments find us.