Augustine wrote his famous City of God in 413 A.D. In it, he describes two cities, the city of the world and the city of God, and calls on society to choose which city it will be a part of. Our challenge as believers is to live in both 'cities' - to be in the world, but not of the world.
It may seem crazy, but the best investment a Christian can make by far is to give of time, talent, and treasure to the Lord. To be a giver reflects the heart of Christ. Where your treasure is, there your heart is. Have you made a conscious decision to give to the Lord?