Read the poem "I Hear America Singing" by Walt Whitman. I hear America singing, the varied carols I hear;
Those of mechanics—each one singing his, as it should be, blithe and strong;
The carpenter singing his, as he measures his plank or beam,
The mason singing his, as he makes ready for work, or leaves off work;
The boatman singing what belongs to him in his boat—
the deckhand singing on the steamboat deck;
The shoemaker singing as he sits on his bench—the hatter singing as he stands;
The wood-cutter's song—the ploughboy's, on his way in the morning, or at the noon intermission, or at sundown;
The delicious singing of the mother—or the young wife at work—or of the girl sewing or washing—Each singing what belongs to her, and to none else;
The day what belongs to the day—At night, the party of young fellows, robust, friendly,
Singing, with open mouths, their strong melodious songs.

What connotation is created with the use of the word "blithe"?

Friendly cooperation
Proud happiness
Reluctant obedience
Responsible diligence