KanjiJLPT N3
Breath

breath, respiration, son, interest (on money), rest, coming to an end

Mnemonic

Sit by oneself in total silence. Feel your heart thumping wildly. Now draw in one deep breath—the heart slows instantly. Every breath reminds you: to calm oneself, just listen to the heart and breathe.
Additional thoughts
Visualize yourself alone in a pitch-dark room. Your heartbeat is deafening. One slow inhale bridges self and heart—that's the kanji: oneself (自) stacked on top of heart (心). Breathing is how oneself keeps the heart alive.
Quick recall
Oneself sits still, heart pounding—one slow breath brings peace.

Details

The keyword for 息 is breath. This kanji refers to the act of breathing, the air inhaled and exhaled from the lungs, and by extension can also mean to rest or take a pause. It conveys the fundamental life process of respiration, connecting the nose and the heart (or mind) as essential elements of staying alive. The concept extends metaphorically to ideas of ceasing or coming to a stop, as in holding one's breath.
On'yomi
そく
Kun'yomi
いき