I was at a bible study recently, and I was very convicted but this word: imaginations of the mind based on insecurities. I find that it's nothing more than covetousness.

Let me give an example. For years as a student riding the bus in middle and high school, I used to imagine myself riding on a motorcycle out the window, on top of the power lines. Or one day bringing my shinai or a katana to school and having people jump out and attack me so I can demonstrate sword-skill (one day, I actually did bring a real dagger from my collection to middle school in my belt as a result on Halloween, uncaught).
I used to imagine I had powers to levitate objects and pick people up with my mind and fling them across the room and make them hit the wall. Or a twin coming to school with me one day and having the women flaunt themselves at him. These are the most embarrassing that I can remember. And I should feel embarrassed. It's nothing more than covetousness - mental idolatry out of my own heart's lusts and pride. Carnal, evil desires. For attention, for whatever else.

"(For the weapons of our warfare are not carnal, but mighty through God to the pulling down of strong holds;)"
"Casting down imaginations, and every high thing that exalteth itself against the knowledge of God, and bringing into captivity every thought to the obedience of Christ;"
"And having in a readiness to revenge all disobedience, when your obedience is fulfilled." 2 Corinthians 10:4-6.

We're to cast down those vain imaginations and thoughts - that stem out of our own insecurities.. They're not of the Spirit of God. We're to renew our minds in the Word, to bring every thought captive to obedience to Christ (Romans 12:2).
Like idolatry - so many times I've found my own mind running away with the world - these ideas I know now are so strange, that I've picked up from watching The Matrix, playing video games, Animes like Akira... Where they'll enrapture and engross your mind into this little world for so long...taking you away into this God-less world, filling you with so many ideas.

I've stopped watching television. I haven't sat down to watch a TV show in almost 2 years, I think. I don't even watch the News anymore! Like, first I just stopped because I couldn't stand watching dirty commercials, and advertising. And raunchy women show their nothings, only things I should see on my wife, and I don't have one yet. And I stopped watching because every show would have some woman's flappy body parts EVERYwhere. I was having these night-dreams. I took the TV out and put it in the garage. And eventually threw it away.

Now, my older sister has her TV in my room, and she watches it, but I can't even stand the sound of it. I can't dare watch it now, it's like watching pornography - disgusting images, all the time, pumping ungodly thinking into my brain that I'd just washed out. No wonder so many of us men of faith are getting divorces - we're called to renew our minds in the Word, and we're soiling them with so much TV! We need to come out of the world. "The world has a lot of stuff wrong with it. Everything," observed my little sister, Marley, who Jesus Christ has saved at age 13.

Do you love the Lord? Do you love Him enough to give Him not just your heart and your spirit, but your MIND TOO? I genuinely don't want to sin against Him because of the work He's done on my heart when He saved me, salvation. Are we seeking after purity, thirsting for righteousness, and practicing Godliness?

I read in 2Peter 1, "...giving all diligence, add to your faith virtue, to virtue knowledge, to knowledge self-control, to self-control perseverance, to perseverance godliness, to godliness brotherly kindness, to brotherly kindness love... Wherefore the rather, brethren, give diligence to make your calling and election sure: for if you do these things, you shall never fall:"

That's just Verses 5-8. Go and read the whole chapter! You'll find, if you're anything like I am, your mind needs much more renewing than you'd thought. I need the Lord to remove 19-20 years of television and worldly thinking.