At the beginning of the Sermon on the Mount, Jesus compares his disciples to salt, light, and a city set on a hill. All these things exist not for themselves, but for something else. In the same way, Christians are meant to make the world a better place. The Christian responsibility is to affect the culture as salt, light, and a city on a hill.
The purpose of the Church is essentially extraverted. It exists for the sake of sanctifying the world. Thus Jesus tells his followers to be light for the world–that which illumines and clarifies the deepest truth of things–and salt for the earth–that which preserves, spices up and frees what is best in creation. We are most fully ourselves when we are a beacon for everyone else.
During the great season of Lent, the Church recommends three very concrete acts: prayer, fasting, and the giving of alms. These are actions that involve the body as much as the mind; and they are things that we “do.” Lent is not so much a time to fuss about one’s “interiority” as a time to get going!”