Reading, I'd say, is a very good thing. It's one of the best things I think God has given us to learn about Him and life and people and all sorts of wonderful things. Reading is one way (of many ways) we feed our brain.
I have a few favorite books. And when a new book comes out that is related to one of my favorite books I really want to read it. I usually wait to see if I can buy it used or if it comes onto my Vine list (a list of things I can choose from to review for Amazon). Sometimes though I buy the book new. I've done this twice this summer. Sadly, I'm throwing one of these books away (and I haven't even finished yet). The writing is good. The author is skilled. But there are scenes in it I wasn't expecting that I shouldn't read. I read one yesterday and parts of that scene keep popping up in my thoughts when I don't want it too. I'm going to have to get a brain cleaning from the Spirit and the Word (this is possible). The book I thought would be really good ended up doing to my brain what bad food does to the body -- clogs it up and causes me to feel a bit yucky.
This kind of thing can happen with anything we expose our brains too -- TV shows and movies and conversations and internet and even our own thoughts. Everything affects our brains in some way -- good or bad. We can reverse the bad effects but it takes intentional effort to do this. There's a reason Paul writes in Philippians 4:8 "whatever is true, whatever is honorable, whatever is right, whatever is pure, whatever is lovely, whatever is of good repute, if there is any excellence and if anything worthy of praise, let your mind dwell on these things."
There's a lot of bad stuff out there, but some of the worst stuff we can fill our minds with originate from ourselves. Jesus says in Matthew 15:19-20 "out of the heart come evil thoughts, murders, adulteries, fornications, thefts, false witness, slanders. These are the things which defile the man;"
If we aren't intentional in our thought life junk will take over and we might find ouselves drowning in disgusting and evil and petty thoughts. If you do a tiny bit of research online about positive and negative thoughts you'll see that it takes at least two or three positive thoughts to get rid of one negative thought. Sometimes it takes ten positive comments to override one negative comment (our words either bless or curse)!
What we think about, what we dwell on affects everything. It will write itself across our facial expressions. Our thoughts will affect the way we interact with others.
So, what are you feeding your brain?