It’s funny but I learned 座右の銘 from a Prince of Tennis song lol, We are 地味’s. In it, I learned two mottos:
石橋を叩かいて渡る - Knock on a stone bridge before crossing it / Be excessively cautious
石の上にも三年さ - Three years on a stone (will make it warm) / Perseverance prevails (which Visits already mentioned)
As for me, I go through various mottos depending on my mood. One that helps me when I’m feeling pulled in too many directions is “Don’t set yourself on fire just to keep others warm.”