Another phrase using 一念:

一念発起
ichi.nen.ho-.kki

Literally: one – idea – emit – wake

Alternately: Firm resolve to carry something through; a sincere and wholehearted intention. Originally used to describe the Buddhist resolve to leave “the world” (i.e. society) behind and take up religious practice, once a common step for aristocrats who had had enough of life at court, the phrase now refers to any such resolution to change one’s ways for the better or achieve a specific goal.

Notes: Make sure you don’t read 発起 as hakki; the main pronunciation of 発 is hatsu but this compound is different.

I firmly resolve never to eat sand again