An action is when a ninja performs a standard attack or mystery, nothing else counts.

Lee fighting spirit is not wholly correct to call it a revive passive instead I would class it as a death denial passive. I've been told that this passive is coded the same way ninjas who revive such as Hidan, Enma, Yugito and etc so its called a revive passive. To my understanding and experience Lee fighting spirit works similarly to Danzo's Izanagi and Hinata[Great Ninja War] passive, instead of taking fatal damage lee will instead gain 10% life therefore if lee hp were to be reduced to zero he will instead be at 10% hp while retaining all status effects applied to him.

Edit: grammer mistake