The truth is, none of us are able to serve the LORD as we ought. I believe, this is why Paul prays for the Ephesians. He prays that God “may grant (them) to be strengthened with power through his Spirit in (their) inner being (Ephesians 3:16).
And he said to them, “This kind cannot be driven out by anything but prayer" (Mark 9:27). Jesus spoke these words to his disciples who failed to cast out a demon. Did it never occur to the disciples to pray before they tried to heal this boy? Absurd! Was this an attitude of self sufficiency? Or arrogance?