As a prisoner, while often looked down on, Paul didn’t consider it a hindrance. Verse 13 specifically asks the Ephesians not to lose heart, which we can think of as being upset or losing faith or confidence in, because of what Paul writes about between the two verses. As long as the Ephesians had heard about God’s grace for them, that would be joined with Israel (still integral to God’s plans). Paul had alluded to this earlier, and it is apparent in all his letters, but here he makes this clear. This is what Paul is a minister of by the grace of God. While this has always been God’s plan, it hadn’t always been expressly revealed, but is to be declared by the church to the world including world powers.