laziness
懈 centers on a state of mental or physical slackness: laziness, neglecting duties, or being idle.
懈 combines 忄 (heart/mind) with 解, which likely contributes the sound and the idea of loosening or slackening, suggesting a mind that has become slack or lazy.
The heart radical 忄 beside 解 (to loosen, untie) paints a picture of a heart that has come untied from effort — pure laziness.
For ケ, imagine a lazy person who can't even finish the word 'ケーキ' (cake) and just sighs 'ke...' while lounging around.
laziness; indolence; negligence (of duties)