I like the whole serenity prayer. The first 4 lines are easy to remember and implement, but the rest is even more biblical.

God, grant me the serenity

to accept the things I cannot change,

the courage to change the things I can,

and the wisdom to know the difference.

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.

Reinhold Niebuhr