Paul knew what he was and whatever he accomplished for good, was God at work in and through him. Therefore, God should receive all the praise. But, he also knew that he could fail and when he did, God wasn't to be blamed. The same should be our sense of recognizing that God should always be honored and due recognition given to Him for any deed that we might do that blesses anyone. And if we fail, or better yet, when we fail, we should be responsible enough to admit our fault and accept the blame.
Peter wept bitterly when he denied the Lord. He knew he had failed. But praise to the Lord for restoring Peter and giving him a renewed calling to bring honor to his Savior.