1. Start with meditating on this statement: "It is what it is."
This statement originates with Luther's Heidelberg Disputation, 1518, where he says,

“19. That per­son does not deserve to be called a the­olo­gian who looks upon the invis­i­ble things of God as though they were clearly per­cep­ti­ble in those things which have actu­ally hap­pened [Rom. 1:20].

“20. He deserves to be called a the­olo­gian, how­ever, who com­pre­hends the vis­i­ble and man­i­fest things of God seen through suf­fer­ing and the cross.

“21. A the­olo­gian of glory calls evil good and good evil. A the­olo­gian of the cross calls the thing what it actu­ally is … [or in some translations, 'says that a thing is what it is.']

UNITSH_119A_SerenityPrayer22. Pray the serenity prayer. Here is the full original version:

The Full Original Copy of the Serenity Prayer
by Reinhold Niebuhr (1892-1971)

God give us grace to accept with serenity the things that cannot be changed,
Courage to change the things which should be changed,
and the Wisdom to distinguish the one from the other.

Living one day at a time,
Enjoying one moment at a time,
Accepting hardship as a pathway to peace,
Taking, as Jesus did,
This sinful world as it is,
Not as I would have it,
Trusting that You will make all things right,
If I surrender to Your will,
So that I may be reasonably happy in this life,
And supremely happy with You forever in the next.

Amen.

3. Read a this chapter from the AA Big Book:
Acceptance was the Answer:

4. Further reading: Byron Katie, 'Loving What Is.'