G-d cares for nothing better, we’re taught, than that we draw close to Him again in repentance if we’d turned away. Now, while we’d logically be expected to do it for that stunning, loving reason alone, the truth is that most of us want to know what it entails beforehand, and then (to use a crass but all-but universal sentiment) what’s in it for us if we do. We’ll touch upon both here, though in reverse order.
It’s vitally important to know first off that “repentance is great”. And why — because “it brings a person closer to G-d”, as Rambam puts it. For, “even if you were a wrongdoer your whole life but you repented in the end, then all of your wrongdoing would go unnoticed” as a consequence.
In fact repenting draws us close to G-d on two levels. Here in this world, by allowing us a deep sense of soul-satisfaction, a surer feeling of being in G-d’s presence, and more. And on an otherworldly level, it ensures us a place in the World to Come, which is “a form of life without death” that is all “pleasantry and goodness”, where the righteous “sit with … crowns on their heads and bask in the radiance of the Divine Presence”.
Don’t mistakenly think, by the way, that those in the World to Come “eat and drink good foods, … dress in (fine) embroidered clothing, dwell in a (house) of ivory, use utensils of gold and silver” or the like, as some imagine. Know instead that, “the great goodness that the soul experiences in the World To Come” is so sublime that “it’s beyond our worldly comprehension”. In fact, we can no more fathom the pleasure of the World to Come than the blind can know the glow and nuance of color or the deaf can sense the hum and ring of sound. For “no one can know its greatness, beauty, and essence other than the Holy One, Blessed Be He”.
Now, as to the actual process of repenting, there are a number of elements involved to simple, conventional repentance. We’re to first of all verbally admit our error to G-d and to the person we’d offended, if that’s the case; second, to simply stop committing the sin and take it upon ourselves to never commit it again; and third, to regret having committed it in the first place.
There are some more demanding things you could do, Rambam points out, like “cry out to G-d constantly and pleadingly; give charity according to (your) means; keep far away from what (you) transgressed against; change (your) name, as if to say, ‘I am someone else; I am not the person who did those things’; change all (your) ways for the good and toward the path of righteousness; and exile (yourself), since exile atones for sins by making (you) submissive, humble and low-spirited”. But they’re not essential.
Finally, you’ll know if you’d truly transformed yourself in the end if you’re faced with the chance to commit the same sin again, but you don’t — and not because someone was watching or because you were physical incapable of doing it, but simply because you’d truly repented.