The first half of a longer section in which Pope John explores the optimal motivation for a citizenry, namely internal:
48. Hence, a regime which governs solely or mainly by means of threats and intimidation or promises of reward, provides (people) with no effective incentive to work for the common good. And even if it did, it would certainly be offensive to the dignity of free and rational human beings. Authority is before all else a moral force. For this reason the appeal of rulers should be to the individual conscience, to the duty which every (person) has of voluntarily contributing to the common good. But since all (people) are equal in natural dignity, no (individual) has the capacity to force internal compliance on another. Only God can do that, for He alone scrutinizes and judges the secret counsels of the heart.
It occurs to me the Western indulgence for “promising” the by-the-bootstrap economic success is on the chopping block here, too. Preaching that people can succeed and grow wealthy in the economic sphere by sheer ingenuity does no good to the betterment of society. For many people it is as unlikely as winning the lottery. Better for all to have a larger share in the benefits of society and motivate all citizens to engagement, rather than make empty promises.
49. Hence, representatives of the State have no power to bind (people) in conscience, unless their own authority is tied to God’s authority, and is a participation in it.( Cf. Leo XIII’s encyclical epistle Diutumum illud, Acta Leonis XIII, 11, 1881, p. 274)
This would be a hard sell within the Church today, and probably impossible outside of it.
50. The application of this principle likewise safeguards the dignity of citizens. Their obedience to civil authorities is never an obedience paid to them as (people). It is in reality an act of homage paid to God, the provident Creator of the universe, who has decreed that (our) dealings with one another be regulated in accordance with that order which He Himself has established. And we (human beings) do not demean ourselves in showing due reverence to God. On the contrary, we are lifted up and ennobled in spirit, for to serve God is to reign.(Cf. ibid., p. 278; also Leo XIII’s encyclical epistle Immortale Dei, Acta Leonis XIII, V, 1885, p. 130)
And no, serving God has no sense of servitude or a loss of a sense of self. It is in giving and serving that we come to our full stature as human beings, becoming all that God has promised. Finding this in serving the state for mere authority’s sake, is especially meaningless in an age where leaders continually fall short of even secular ideals.