You could be good today. But instead you choose tomorrow. - Marcus Aurelius

Some people, when they do someone a favor, are always looking for a chance to call it in. And some aren't, but they're still aware of it--still regard it as a debt. But others don't even do that. They're like a vine that produces grapes without looking for anything in return. (Hays translation)

Ask yourself at every moment, ‘Is this necessary?’

To accept it without arrogance, to let it go with indifference. (Hays translation)