The first form [in which service to others] is undertaken consists in the commitment and efforts to renew oneself interiorly...Social institutions do not of themselves guarantee, as if automatically, the common good; the 'renewal of the Christian spirit' must precede the commitment to improve society...Two things that I think are worth noting here: first, the recognition that despite the fact that the social doctrine of the Church is expressed in the Compendium in terms of the natural law, so as to commend it to non-Catholics as well as Catholics, it seems that this passage acknowledges that apart from conversion of hearts to Christ, the social doctrine will never be properly implemented. This is because the charity that the social doctrine requires is not a natural thing, but a gift from God. Consequently before we can properly serve others, we must be renewed in our hearts and minds ourselves.
It is from the conversion of hearts that there arises concern for others, loved as brothers or sisters. ... The laity must therefore work at the same time for the conversion of hearts and the improvement of structures... (Compendium, 552; emphasis in original print version).
The second and, for some non-Catholics, perhaps the more surprising thing is that the Magisterium here repeats the call, also found in Vatican II, for the laity to be involved in the work of evangelism.