The rule of St. Benedict, and monastic traditions in general, often give the vibe of military type training. At first, the soldier may despise discipline. His commanding officer may be severe and the initially soft individual must become strong. After his training, the soldier can look back and appreciate the discipline imposed on him by his commander. The soldier is a new kind of person, and he owes it to the training.
In Christian monasticism, the disciple is training to perfect the soul. He is training to develop purity of heart and to become the kind of person who does the Good – serves the will of God – naturally.
“Now, therefore, after ascending all these steps of humility, the monk will quickly arrive at that perfect love of God which casts out fear. Through this love, all that he once performed with dread, he will now begin to observe without effort, as though naturally, from habit, no longer out of fear of hell, but out of love for Christ, good habit and delight in virtue. All this the Lord will by the Holy Spirit graciously manifest in his workman now cleansed of vices and sins.”
Fear of hell is specifically mentioned several times as a motivator for behavior in the Rule of St. Benedict (as it is in the New Testament), but is also relativized by texts such as these.
When the monk is further down the road to perfection, love becomes the primary motivator and his purified actions come naturally.