The speaker lists small failures: forgetting to smile, forgetting to eat, and finally forgetting how to live. Each line is a little bigger than the last, so the poem slides from everyday neglect to a total loss of the will to go on. Nothing is said about what caused this, which makes the emptiness feel even heavier. The title, "mistake," suggests the speaker sees all of this as their own fault.
Then the tone shifts. "Don't blame yourself" sounds like comfort, but the next line undoes it: "no one wants someone needy." The speaker seems to be talking to themselves, or repeating something they've been told, and the kindness turns into a cold verdict. Needing help is treated as the real mistake.
The mood is bleak, quiet, and lonely. The short lines and lowercase style make the voice feel small and worn down, like someone who has already decided not to ask for anything.