The old rebbe explains in the 26th chapter that just like when two people have a fight, if one of them is lazy he will be beaten even if he is stronger. So too by the person who fights his bad instinct, if he will be sad and lazy, he will be beaten by it. And therefore one should be quick, which this comes from happiness, and through this he will overcome the bad. The old rebbe asks: it says that something good comes out of the sadness, so why should we not be sad?

The old Rebbe answers: the meaning of that is that the sadness itself is not good, however, something good could come from it, and this good thing is the happiness which comes after the sadness.because when someone is sad because he sinned, that means he regrets it and he wants to fix it, and when he is really heartbroken because of it, the impurity also breaks, and then he will be happy, and the happiness will be a real happiness.

Now the old Rebbe explains how to get rid of the sadness which comes because of worldly things as kid, financial or life: if everything which happens to him, even if it looks bad, he will accept happily through thinking to himself that we do not understand why G-d does this, but G-d has a reason for everything, and therefore even the bad thing which happened are really for the good. And if he thinks about this, he will get rid of the sadness.

Now the old Rebbe explains that one also needs to get rid of sadness which comes because of spirituality, because if one is learning Torah or praying, or even in his business, if he becomes sad because he sinned, he has to remove the sadness. Since it really comes from the bad which wants him to sin again, because if not so, where did the sadness come from in middle of his work if he didn’t think of it. And therefore he should think to himself that it's not the time to be sad, even if it is because he did a big sin. Rather, one needs to set a time to get himself to be heartbroken, and then the impurity will also break. And after he got to be really heartbroken, he should not think about the sin anymore, and he should be sure that G-d forgave him.