Rabbi Yisroel Salanter used to say, "There is no greater illness than discouragement." At times a person may take note of all his faults and failures and give up hope of improving. But when it comes to monetary wealth, a person tries to gather as much money as possible even if he will not become wealthy. Someone suffering physical pain also tries to alleviate some of the pain even if he is unable to bring about a complete cure. Rabbi Salanter said our attitude towards refraining from evil and performing good deeds should be the same. Even if someone will be far from perfect, he should at least try to do as many good deeds as possible and refrain from violating as many prohibitions as he can.