We would do good works out of a sense of duty and not out of love. We would become resentful and bitter about what we perceive to be a cruel task-master in heaven. The Gospel produces good works. Good works are always a response to God's good news. Works that are performed under the threat of punishment are not good works.
Good works are works of love.
It is the Holy Spirit, however, who puts such eagerness of unconstrained love into the heart, as Paul says in ch. But the Spirit is given only in, with, and through faith in Jesus Christ, as Paul says in his introduction. So, too, faith comes only through the word of God, the Gospel, that preaches Christ. After we have been justified and regenerated by faith, therefore, we begin to fear and love God, to pray and expect help from him, to thank and praise him, and to submit to him in our afflictions. Then we also begin to love our neighbour because our hearts have spiritual and holy impulses.