“Because of the very fact that pleasure is our primary and congenital good we do not select every pleasure; there are times when we forgo certain pleasures, particularly when they are followed by too much unpleasantness.
Furthermore, we regard certain states of pain as preferable to pleasures, particularly when greater satisfaction results from our having submitted to discomforts for a long period of time.
Thus every pleasure is a good by reason of its having a nature akin to our own, but not every pleasure is desirable. In like manner every state of pain is an evil, but not all pains are uniformly to be rejected.
At any rate, it is our duty to judge all such cases by measuring pleasures against pains, with a view to their respective assets and liabilities, inasmuch as we do experience the good as being bad at times and, contrariwise, the bad as being good.” (Letter to Menoeceus, 2)
Epicurus on pleasure vs pain