台Taivo A Taiwan Mandarin dictionary

習慣成自然

xíguànchéngzìrán

ㄒㄧˊ ㄍㄨㄢˋ ㄔㄥˊ ㄗˋ ㄖㄢˊ

Simplified 习惯成自然

1(saying) habit becomes second nature; to do something as if it were perfectly natural because one is accustomed to it

Keep 習慣成自然 and it comes back until you know it.