The Gift that Perfects Will - God is My Strength. Fr. Bede Jarrett

This gift is fortitude, which, as we have already stated in general terms, must be carefully distinguished from the virtue of fortitude. This gift is entirely under the direction of God and excludes altogether on my part any action at all in the operation of the gift. This exclusion of all cooperation seems harder perhaps to understand when the will is in question, as it is in the gift of fortitude. It seems altogether impossible to imagine that God can direct the will and yet that it should not be voluntary.

It is clear, indeed, from the Catholic doctrine of grace, that it is possible for God to move the will so powerfully as to determine not merely that the will shall act, but to determine also that it shall act freely. God is so intimate to the will that He can, so to say, save it from within. However, this is different from His control of the will in the gift of fortitude. In the intellect, a light can be present that is none of our own. However, in the will, how can there be a force that is not itself of the will?
In other words, we must reconcile two contradictory ideas—namely, a will that acts yet does not merit. I am apparently and actually perfectly free, for God does not compel the will unwillingly. Yet, with all my freedom under the guidance of the gift, I cannot acquire merit. That is what we said was the very characteristic of the sevenfold gifts—that they are, in their proper operation, entirely the work of God.