There is much joy to be found in the sentiment that we are saved by faith, not by the following of rules. It is sad that we are unable to continually hold onto this joy. So often we still get weighed down by feeling like we aren’t doing enough, or that we must do more to be good enough. “Enough” gets in the way so often. But we are saved merely through faith.
Paul fully understands this and he acts upon it. I mean this in that he does not act as though his actions or his own strength are what gives him power, but that his faith in Christ and knowing that he is with him gives him that power. As such, many people are able to see the glory of God shining through him. Christ is enough for him, and he doesn’t worry about anything else.