For love to grow in earnest, it needs time, repetition in memory at least, and the reiterated and accumulated excitation of wonder and beauty.
The same process may be said to hold for anger and hatred as well; an emotion needs to work itself up in the imagination, otherwise, it remains a passing sensation of attraction, irritation, etc.
Most resentment and lasting hatred is a product of mulling over a grievance, lingering on a real or imagined reason for believing that the other has somehow injured one's pride.
It's a matter of repeating a thought, five, ten, a hundred times until it becomes a certainty.
In other words, there is a dynamic function of the soul involved in almost every conviction or lasting emotion.
The Hebrew language often describes this in the reflexive form of the grammatical structure of the verb, to be enraged, to be in love, enraptured, etc.
A person makes his selfhood, creates his passion or his belief.
Insofar as faith is concerned, we do not set up a new system of conviction; we use that which exists.
Only our goal is different.
The soul reaches exalted states by way of contemplation or meditation, in the sense of dwelling on the source of wonder and inner joy.
Such a person may insist that he has never meditated in the customary way of removing himself from the world, but if he were made to realize that almost all of his deep feelings, ideas, and desires are a product of brooding over a thought, repeating and nurturing a sensation, the concept of meditation would become more comprehensible.
Worry, incidentally, has the same quality.
One lets a fearful thought return again and again, with or without variations perhaps, but with a tendency to accumulate force until it becomes painful and a source of suffering.
Creative cogitation can prove disastrous.
In other words, the structure of the mind is such that with meditation anything can become a powerful reality for one.
So too, the command "And thou shalt love the Lord, thy God," has to be allowed to grow in a person.
It is obviously not the sort of order that one carries out automatically.
It is a directive to meditate as well as to feel.
The meditation involved is a matter of cogitation as well as repetition and emotional nurturing.
–Rabbi Adin Steinsaltz
From "Implications of the Menorah" in The Candle of God by Rabbi Adin Steinsaltz