Many people believe that admitting fault means they no longer have to correct it.
--Marie von Ebner-Eschenbach
It is not so. Admitting means that first of all you agree with your conscious that you made a mistake. And mistakes, by nature, have to be corrected. Remember, mistakes are committed only once or twice. Next time you behave in the same way, it is called deliberate behavior.

An error confessed, May yet be blessed,
An error denied, Is multiplied
--Bremer Hofmeyr
The same explanation implies for this too. Because when you confess an error, you try to correct it; and if you don't, you behave in the same way. This goes on and goes on till a long list can be prepared of those errors.

When you realize you've made a mistake, take immediate steps to correct it.

Good to forgive, best to forget.
--Robert Brown, "Le Saisiaz"

To err is human, to forgive is divine.
--Alexander Pope

"Holding on to anger is like grasping a hot coal with the intent of throwing it at someone else; you are the one who gets burned."
--Buddha

Forgetting cannot be forgiven, but forgiving shall not be forgotten.

Happiness comes from the health of the soul.
--Aeschylus

Happiness is a fragile bubble
Forget yourself, its size will double,
But selfish greed and lustful thirst,
Will only make your bubble burst.
--Peter Tongeman

Pleasures of the mind are the greatest, those of honor are inferior, and the physical pleasures come last of all.
--Plato
This comes with practice and contentment.

There is such a thing as pleasure, and there is its opposite pain, but there is also a mental state which is neither one nor the other : between the two is a state of the rest of the soul.
Try to achieve that

The absence of desires is the gate of happiness.
Try to implement it in your life, you will feel happier and more satisfied than ever.