seren- +

I count only the hours that are serene.

A 19th century motto on a sundial near Venice by British essayist William Hazlitt.

1. A song used to court somebody, traditionally sung by a man in the evening outside a woman's window, or the performance of such a song.
2. An instrumental work similar to a sonata, designed for evening outdoor performance by a small ensemble of musicians.
3. Etymology: "musical performance at night in open air"; especially, one given by a lover under the window of his lady; from French sérénade, from Italian serenata, "an evening song".

Literally, "calm sky" from sereno, "the open air"; the noun use of sereno, "clear, calm"; from Latin serenus, "peaceful, calm, serene".

Someone who performs a serenade in honor of someone; such as, the lady of special interest to the person.

1. Without worry, stress, or disturbance.
2. Unaffected by disturbance; calm and unruffled.
3. Bright and without clouds.

1. In a peacefully serene manner.
2. Calmly; quietly.

1. Marked by, or suggestive of, utter calm and unruffled repose or quietude.
2. Characterized by the absence of emotional agitation.
3. Also a reference to the calm conditions of the weather.

Calmness.

1. A mental, or emotional, disposition free from stress or emotion.
2. The absence of mental stress or anxiety.
3. A title of honor, respect, or reverence, used in speaking of or to certain members of royalty: "We are here to honor her royal serenity."

Serenity Prayers

Apparently of unconfirmed authorships.

• God grant me the serenity to accept the things I cannot change.
• God, give us grace to accept with serenity the things that cannot be changed, courage to change the things that should be changed, and the wisdom to distinguish the one from the other.
• O God and Heavenly Father,
  Grant to us the serenity of mind to accept that which cannot be changed; the courage to change that which can be changed, and the wisdom to know the one from the other, through Jesus Christ our Lord, Amen.
• God grant me the serenity
  To accept the things I cannot change;
  Courage to change the things I can;
  And wisdom to know the difference.
  Living one day at a time;
  Enjoying one moment at a time;
  Accepting hardships as the pathway to peace;
  Taking, as He did, this sinful world
  As it is, not as I would have it;
  Trusting that He will make all things right
  If I surrender to His Will;
  So that I may be reasonably happy in this life
  And supremely happy with Him
  Forever and ever in the next.

Generations of recovering alcoholics, soldiers, weary parents, exploited workers, and just about anyone feeling beaten down by life have found solace in one, or more, of the prayers shown above.