Giving is a tangible act of worship.  And really, it's never something that starts with us.  All of our giving to God is a giving back--giving back to God a portion of what He has already given to us.  The Scriptures tell us that God has given us everything we need, and that every good thing we have is from God.  And yet, even so, when we give, God promises us even more blessings in return!