Lethargic: Adjective /ləˈθɑː.dʒɪk/
lacking in energy; feeling unwilling and unable to do anything, tired, phlegmatic, sluggish, weary, lackluster, languid, indolent, exhausted, lifeless:
The obese teenager seems lethargic after eating so much food due to his voracious appetite.
Afternoon is the time when everybody tends to be lethargic.
Being old doesn’t necessarily mean to be lethargic.
You should have stopped being lethargic because being lethargic is a harbinger of failure.