This fact is shown very clearly in the character of Macbeth. He is driven to the immoral, "evil" side largely in part by his wife's persuasive tactics and because of his fear of how people will view him. Macbeth constantly strives to impress everyone in the society in which he lives, even if it means putting up a "false-face," or attempting to externally appear differently from what his internal thoughts would naturally reflect.
Lady Macbeth says to her husband, questioning his manhood in an attempt to convince him that he must kill King Duncan, "Wouldst thou have that / Which thou esteem'st the ornament of life, / And live a coward in thine own esteem, / Letting "I dare not" wait upon "I would," / Like the poor cat i' th' adage?" (Macbeth, 1.7). She succeeds in her aim, for Macbeth agrees to go along with the murder, showing that she has turned him to the "evil" side, by mocking him and intentionally instilling fear in him. She wants to say things to her husband that will induce a change in mindset and a change in his course of action, and being that this actually works and that she achieves her goal, we can clearly see that Macbeth is very easily influenced by external forces and opinions - he cares a whole lot about what other people think of him, and many argue that this is the cause of his eventual downfall as a tragic hero.
Because Macbeth lets these outside forces get the best of him and prompt his actions, he suffers many consequences, especially internally. We see many instances in the play of Macbeth's character being destroyed by guilt of his "evil" wrongdoings, and even his increasing insanity and mental disorder. All of these negative consequences stem from his immoral character, and we see this not only in Macbeth, but also in our daily lives. Many people who turn "evil," or simply commit a crime or something that goes against their moral sense, end up feeling extremely guilty, and letting those feelings consume them and tear them apart internally.
One specific example of Macbeth's guilt as a result of "choosing evil" comes from Act 2, Scene 1 when he has a soliloquy that involves a dagger - a dagger that is very likely only a figment of his imagination, a symbol of the guilt he feels after killing Duncan. Macbeth says, "Or art thou but / A dagger of the mind, a false creation / Proceeding from the heat-oppressed brain?" (Macbeth 2.1). Here, Macbeth is directly referencing the fact that there is a very good chance that there is not even a dagger in his hand, and that he is just imagining the whole thing. He also addresses his "heat-oppressed brain," slowly being wrecked by mental illness, resulting from the guilt building up inside of him with each evil action he commits.
Love this because it implies that there is a direct relationship between Macbeth's visions of daggers (guilt) and him killing people (murder). It's as if he doesn't understand that he will never get better, mentally or emotionally, until he fixes himself morally and corrects his evil actions, misconduct, and wrongdoings. You gotta' stop murdering people, bro...#smh...
