Other people's views and troubles can be contagious. Don't sabotage yourself by unwittingly adopting negative, unproductive attitudes through your as… - Epictetus

Si alguien te hiciere saber que un inviduo habla mal de ti, no te defiendas, ni refutes lo que haya dicho, sino que responde: «Aquel que ha dicho aquello de mí, ignora sin duda otros defectos, de lo contrario no habría dicho sólo estos.»

Whether human affairs are directed by Fate’s unalterable necessity, or by chance, is a question. The wisest of philosophers disagree on this point. [Epicureans] insist that heaven is unconcerned with our birth and death – is unconcerned, in fact, with human beings generally – with the result that good people often suffer while wicked people thrive. [The Stoics] disagree, maintaining that although things happen according to fate, this depends not on the movement of the planets but on the principles and logic of natural causality. This school concedes to us the freedom to choose our own lives. Once the choice is made, however, the Stoics warn that the subsequent sequence of events cannot be altered. With regard to practical matters they maintain that popular ideas of good and bad are wrong: many people who appear to be in dire circumstances are actually happy provided they deal with their situation bravely; others, regardless of how many possessions they have, are miserable, because they do not know how to use the gifts of fortune wisely.

So if you like doing something, do it regularly; if you don't like doing something, make a habit of doing something different.