As the old saying goes, "an idle mind is the devil's playgorund." Now whether you have an idle mind at the moment, or it's going 100 miles an hour, remember this, satan and his minions will take you down mentally whenever they can. Why? Because when you are feeling down, you are a MUCH easier target for their attacks.
When a relationship isn't working out, someone at work is trying your last nerve, or you keep thinking about past mistakes, you tend to think of activities that will give you an artificial "pick me up". Unfortunately, many of those "pleasures" tend to be the very tools of the enemy. Whether it's alcohol, drugs, sex, or even simply turning to anger and lashing out at all those around you to make YOURSELF feel better, these behaviors will just make you feel worse when the "high" wears off. The bottom line is NONE of these selfish activities will give your mind any lasting peace, and NONE will remove the negative thoughts that satan has planted there.
A much better way of handling these attacks is to do the following. First, recognize what the enemy is up to. When you find yourself "`dwelling" on a situation, or something in your past, know that satan is up there, planting away his seeds of discontnent and despair. Don't get me wrong, we will definitely encounter struggles now and then, but the key is to deal with them as soon as we can, and then let them go. Second, when under attack, turn to God through prayer, scripture and song. Once you feel a situation getting the better of you, turn to the Lord for comfort and strength to pull you through it. Lastly, know you are ALWAYS loved by your Heavenly Father, "no matter what" you do, say or are feeling. Don't be fooled by the devil and his tactics of making you feel unworthy, ashamed or unwanted. God loves you so much that, "He gave his only Son, so that everyone who believes in Him may not die but have eternal life." (John 3:16)
The enemy may be able to manipulate your mind, but there's NO room in your "heart" for their lies if Jesus is living there. Has He taken up residence yet? If not, know this, Jesus is at the door to your heart and is knocking. All you have to do is open it and let Him in.