Teshuva is a world unto itself, embracing two apparent opposites.
On the one hand, it is an exceedingly lengthy path which, in fact, has no end point.
When a person wants to attain teshuva, whatever his starting point, each subsequent moment of change throughout life becomes the fulfillment of that initial inner resolution to make the turn.
On the other hand, teshuva is a tiny point, a turnabout in miniature.
Teshuva is a moment of reflection, remorse, and thought of change, a flash of insight that instructs a person to change and improve.
These two aspects of teshuva are not contradictory, but complementary.
In one respect, there is nothing more difficult than doing teshuva, because teshuva means transforming oneself, fashioning a new nature.
In another respect, there is nothing easier than teshuva; a split second of turning is already considered teshuva.
The ba’al teshuva (penitent) is thus like a person following a certain course who in an instant decides to change his direction.
From that point onward, he no longer goes the old way, but follows a different path.
Yet the new path, like the old one, is long and unending.
–Rabbi Adin Steinsaltz