The Church's deepest nature is expressed in her three-fold responsibility: of proclaiming the Word of God (kerygma-martyria), celebrating the sacraments (leitourgia), and exercising the ministry of charity (diakonia). These duties presuppose each other and are inseparable. For the Church, charity is not a kind of welfare activity which would equally well be left to others, but is a part of her nature, an indispensable expression of her very being.
The Church is God's family in the world. In this family no one ought to go without the necessities of life. Yet at the same time caritas-agape extends beyond the frontiers of the Church. The parable of the Good Samaritan remains as a standard which imposes universal love toward the needy whom we encounter "by chance" (cf. Lk 10:31), whoever they may be. (pg. 33).
Significantly, our time has also seen the growth and spread of different kinds of volunteer work, which assume responsibility for providing a variety of services. I wish here to offer a special word of gratitude and appreciation to all those who take part in these activities in whatever way. For young people, this widespread involvement constitutes a school of life which offers them a formation in solidarity and in readiness to offer others not simply material aid but their very selves. The anti-culture of death, which finds expression for example in drug use, is thus countered by an unselfish love which shows itself to be a culture of life by the very willingness to "lose itself" (cf. Lk 17:33 et passim) for others. (pg. 43)
It's neat to see the Pope express the benefit to young people of doing works of service. I was trying to argue something along these lines in my essay in The Catholic Homeschool Companion on homeschooling teens entitled: "Apologetics: Sacraments, Service and Study".