“Even if other people don’t find out what you did, you’ll always know.”
This was one of my dad’s mantras (along with “at a buffet, make them lose $ or don’t go.)
His thought was that you don’t have to get caught doing something wrong to know you shouldn’t do something wrong.
I think of that a lot, and am always thankful to have had it embedded in me at such a young age. While I certainly haven’t been perfect, I can say my mistakes have stemmed from stupidity or anger, rather than from deliberate actions (assuming I won’t get caught).