The Chinese character 心 xīn is the heart.
门 mén door, gate
A heart 心 xīn indoors 门 mén is bored 闷 (mēn/mèn).
亚 yà sub, inferior
An evil 恶 è heart is an inferior 亚 yà one.
亠 tóu lid and 匸 xì cover
A heart 心 xīn that is enclosed / covered 匸 xì with a lid 亠 tóu 忘 wàng forgets / neglects.
See also 亠 tóu lid and 匸 xì cover with eye 目 mù.