Who is responsible for our own restlessness. That no one obstructs us. That it's all in how you perceive it. - 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)

Self-control and resistance to distractions. Optimism in adversity—especially illness. (Hays translation)

Think not so much of what thou hast not as of what thou hast: but of the things which thou hast, select the best, and then reflect how eagerly they would have been sought, if thou hadst them not. At the same time, however, take care that thou dost not, through being so pleased with them, accustom thyself to overvalue them, so as to be disturbed if ever thou shouldst not have them.