Choices

"Satan has many reasons for doing what he does. Perhaps the most powerful is the motive of revenge, but he also wants to make men and women  miserable like he is miserable. Each choice you and I make is a test of our agency-whether we choose to be obedient or disobedient to the commandments of God is actually a choice between "liberty and eternal life" and "Captivity and death." Elder L. Tom Perry "Obedience to Law is Liberty" General Conference April 2013

When we do something wrong we are no longer free. We are not tied down and we have given up our agency. Those who chose to do drugs once thought it was the freedom to do them, now find themselves tied down to something they can no longer control. Those who were free to watch inappropriate videos, now find themselves losing their self control.

Satan knows everyone weaknesses and he uses them to make us miserable like himself. That is why we need to be obedient and guard our agency.