אות-לד

The essential matter is to strengthen oneself in joy, through every manner of advice — for sadness is very harmful. One must therefore strive with all one's strength to distance and banish sadness and melancholy — both through seeking and finding good points in oneself, and through [the blessing] that He did not make us a nation. And often it is impossible to gladden oneself except through matters of light-heartedness and humor, etc. — as we have written regarding this in the section on joy. (ibid.)