Some of the reasons offered in the Psalms for long-term optimism. According to Wikipedia “Optimism is an attitude reflecting a belief or hope that the outcome of some specific endeavor, or outcomes in general, will be positive, favorable, and desirable.” Optimism is basically a hopeful mode about something when there is not too much hope to have. Apparently there are ten Psalms about hope. One is Psalms 34:17-20:
When the righteous cry for help, the Lord hears,
and rescues them from all their troubles.
The Lord is near to the brokenhearted,
and saves the crushed in spirit.
Many are the afflictions of the righteous,
but the Lord rescues them from them all.
He keeps all their bones;
not one of them will be broken.
There is also Psalm 71: 1-6
In you, O Lord, I take refuge;
let me never be put to shame.
In your righteousness deliver me and rescue me;
incline your ear to me and save me.
Be to me a rock of refuge,
a strong fortress, to save me,
for you are my rock and my fortress.
Rescue me, O my God, from the hand of the wicked,
from the grasp of the unjust and cruel.
For you, O Lord, are my hope,
my trust, O Lord, from my youth.
Upon you I have leaned from my birth;
it was you who took me from my mother’s womb.
My praise is continually of you…
A lot of long-termed optimism is David asking God to deliver him from his enemies. One of these is Psalm 59:
1 Deliver me from my enemies, O God;
be my fortress against those who are attacking me.
2 Deliver me from evildoers
and save me from those who are after my blood.
3 See how they lie in wait for me!
Fierce men conspire against me
for no offense or sin of mine, Lord.
4 I have done no wrong, yet they are ready to attack me.
Arise to help me; look on my plight!
5 You, Lord God Almighty,
you who are the God of Israel,
rouse yourself to punish all the nations;
show no mercy to wicked traitors.c]
6 They return at evening,
snarling like dogs,
and prowl about the city.
7 See what they spew from their mouths—
the words from their lips are sharp as swords,
and they think, “Who can hear us?”
8 But you laugh at them, Lord;
you scoff at all those nations.
9 You are my strength, I watch for you;
you, God, are my fortress,
10 my God on whom I can rely.
God will go before me
and will let me gloat over those who slander me.
11 But do not kill them, Lord our shield,d]
or my people will forget.
In your might uproot them
and bring them down.
12 For the sins of their mouths,
for the words of their lips,
let them be caught in their pride.
For the curses and lies they utter,
13 consume them in your wrath,
consume them till they are no more.
Then it will be known to the ends of the earth
that God rules over Jacob.
14 They return at evening,
snarling like dogs,
and prowl about the city.
15 They wander about for food
and howl if not satisfied.
16 But I will sing of your strength,
in the morning I will sing of your love;
for you are my fortress,
my refuge in times of trouble.
17 You are my strength, I sing praise to you;
you, God, are my fortress,
my God on whom I can rely.
In this Psalm David is asking for deliverance from his enemies. He has optimism that God will save him from his enemies (which He does). That is what men faithful to God do. They pray and have optimism that God will answer their prayers.