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.