Your conscience tells you to five for others according to the Principle. No matter how strong your body’s desire is, if you intentionally increase the force of your conscience beyond the force of your body, your body will follow it. If you cannot, you had better decrease your body’s force through fasting and asceticism. If clear water continually flows into a muddy pond, eventually the pond will become clear.
Source
P. 1519, par. 5
Remark
A process is implied that strengthens the power of conscience.
In addition, this quote makes it clear that asceticism is only a tool that is needed above all when one has no access to the power of love or to one's heart and conscience.