We get to!
Faith without works is dead. Without obedience on our part there is no salvation possible. The Gospel relationship is purely bi-directional but without the blood of Jesus Christ there is no remission of sins. You cannot have a workless gospel as we were created in the first place for good works. If you think producing good works purely for the glory of God is too much for whatever reason then you miss the point of God's Gospel plan of salvation altogether. Its not that we have to, we get to serve our Lord.