In the life of an individual man, virtue is the sole good; such things as health, happiness, possessions, are of no account. Since virtue resides in the will, everything really good or bad in a man’s life depends only upon himself. He may become poor, but what of it? He can still be virtuous.
 Bertrand Russell, A History of Western Philosophy (1945). copy citation

Context

“Virtue consists in a will which is in agreement with Nature. The wicked, though perforce they obey God’s law, do so involuntarily; in the simile of Cleanthes, they are like a dog tied to a cart, and compelled to go wherever it goes.
In the life of an individual man, virtue is the sole good; such things as health, happiness, possessions, are of no account. Since virtue resides in the will, everything really good or bad in a man’s life depends only upon himself. He may become poor, but what of it? He can still be virtuous. A tyrant may put him in prison, but he can still persevere in living in harmony with Nature. He may be sentenced to death, but he can die nobly, like Socrates. Other men have power only over externals; virtue, which alone is truly good, rests entirely with the individual.” source