You are correct, there is nothing we can do on our own to enter Heaven. However, after baptism, being born again, being "in Christ", we are called to follow our faith and put it into action - feeding the hungry, ministering to others, etc. Both are essential. We read in the epistle of St. James that "faith without works is dead." As a matter of fact, the only place in the Sacred Text that we see the work faith and alone together, the words "not by" are in front of them. We find that in James 2:24, "You see that a man is justified by works and not by faith alone." But I'm sure you already know this.