In a trade, keep your end even if they’d never notice you didn’t.

Most deals have a part the other side cannot verify. They are not counting, or they would not know the difference, and that gap is where people quietly shave a little off and call it fine. Keeping your end inside the gap is the only way to find out whether you are honest or just observed.

Finish the next swap exactly as described, down to the thing they would not have checked. Then notice how it feels to be owed nothing and to owe nothing. That particular lightness is the actual return on the deal.