A lovely word, I think. A pleasant feeling of freedom from any need to exert onself, to
relax and enjoy il dolce far niente.
From biograph of Plutarch:
" “If a man were called to fix the period in
the history of the world during which the condition of the human
race was most happy and prosperous, he would,” says Gibbon,
“without hesitation, name that” in which Plutarch wrote. It was
the twilight time of antiquity; and in the works of Plutarch 1 are
clearly mirrored the charm and languor, the incentive to stroll and
loiter, and the dimming of vision, characteristic of the hour
before “the sun sank and all the ways were darkened.”

Bur my dictionary give it a pejorative slant I think questionable:

languor
n.
5ME langour < OFr langueur < L languor < languere, to be weary: see LANGUID6
1 a lack of vigor or vitality; weakness
2 a lack of interest or spirit; feeling of listlessness; indifference
3 the condition of being still, sluggish, or dull
lan4guor[ous
adj.
lan4guor[ous[ly
adv.

1