This week's parsha relates how the spies came back from the Land of Israel with a derogatory report. As the Torah tells us, they were severely punished, and they died, "in the plague before Hashem" (Devarim 14, 37). Rashi explains that they died with an appropriate death that matched their sin, for as we know Hashem metes out punishments measure for measure. Their tongues stretched until they reached their navels and worms exited their tongues and entered their navels.
Rav Wolbe (Shiurei Chumash) comments that it is clear how the first part of this horrible death corresponds to their transgression. Since they used their tongues to speak lashon hara about Eretz Yisroel, their tongues stretched out in a ghastly manner. However, Rav Wolbe asks, what is the measure for measure involved with the worms that left their tongues and entered their bodies? He answers that one who speaks lashon hara is in affect killing himself. As Chazal tell us, lashon hara kills three people: the one who says it, the one who hears it, and the one about whom it is said. The words of lashon hara, so to speak, are like daggers that leave a person's mouth and enter his body. It can be likened to worms that leave the tongue and enter the naval, hence, the measure for measure in their deaths.
Being that lashon hara is so terrible, what can one do to break this bad habit? Theoretically, he could refrain from speaking gossip for an entire day, but the next day he might very well end up "paying interest" and speak twice as much as usual. He simply closed his mouth, but he did not treat the root of the problem; the evil trait that lies inside him. Rather, a person has to acquire and maintain a positive outlook on others.
While in Stockholm, Rav Wolbe came in contact with a woman about whom he declared that it was impossible to speak lashon hara in her presence. When she heard someone speak disparagingly about another, she would say, "If that is the case then we must help him. How can we help him?" The proper method of rectifying this middah is to acquire what Chazal call an "ayin tova" (a good eye). If one maintains such an outlook he will never come to speak derogatorily about another.