Why should parents teach their children to do chores? Although there are many good reasons, one of the best (that is rarely thought about) is to teach the children that since they are a part of the family, they are expected to invest themselves in the life of the family. A six year old may not be able to cook all the meals like Mom, nor be able to work a full time job like Dad, but he can take out the trash and rake leaves. He does his part by giving of himself to show that he is part of the household. He is not "buying" his food and clothing, as though he were merely a renter (though lack of teaching can make it seem like this). Now let us take that one step further...
Why do you tithe? Is it really to help the church pay her bills? No, that is only a bonus (church's had no "bills" per se in the first centuries, but Catholics were still required to tithe). You tithe because it is a personal sacrifice that you make because you are doing your part to show that you are a part of everything that goes on in the parish. This is why giving to your parish is one of the Precepts of the Church (and thus not negotiable). Those who can give and do not give to the Church are saying that they are not part of it (and maybe they are not!). Those who give far less than they are able are saying that they are only a small part of the parish. We give because it is our parish and we are one of its members.
Another reason we give to the Church is to remind us that God's grace is free, but that we must never think it is cheap. Tithing tells us that we need to be "invested" in our parish in a spiritual and physical way--you aren't truly "buying stuff" for the parish, you are giving of yourself to show to others that you see a value in the parish's existence. This is also one of the main reasons the Church says you are expected to give a stipend in a Mass intention -- it is a personal sacrifice to show that you see a value in the Mass and the spiritual benefit that will come from the intention, and that you want to invest yourself personally in it. Unless the person is unable to give (which does not prevent the intention from being done), his stipend is his declaration that he is a part of that specific Mass for that specific intention. Words are easy; a personal sacrifice goes much deeper.
If you give to a poor person on the street, you have done something in his life. If you give to the Church you have done something in her life. All that we do should show that we invest ourselves in the work we are doing, and never do anything that is good in a half hearted way or without true commitment. Give as Christ calls us to give; cheerfully and with personal involvement and devotion to the work of the Kingdom of God.