"Do not be conformed to this world, but be transformed by the renewal of your mind, so that you may prove what is the good and acceptable perfect will of God, even the thing which is good and acceptable and perfect."
Keep your mind on the positive, straight, and narrow path is harder than you think.
Renewing your mind is not easy. We renew insurance in our lives and it takes one phone call. A driver's license, one visit to the online DMV. And we don't have to do it again for a year or a bit longer. Renewing your mind is more like undertaking the job of renewing and refurbishing an old house. It doesn't happen quickly; it takes time, energy and effort, and there is always something that needs attention.
Don't get hung up on thinking you can pray, and it will just fall in your lap without much effort. To get the mind renewed, you have to think right thoughts over and over again, until they become rooted in your thinking - until right thoughts come to you more easily and naturally than wrong thoughts.
You actually have to discipline yourself to think properly, and you will have to guard against falling into old thought patterns, which can happen very easily. When it does, don't feel bad - just start thinking rightly again. You will eventually come to the place where wrong thoughts make you feel uncomfortable and they just don't fit into your thinking process any longer.
I know you've been practicing this for the last couple of weeks, and you've gotten a tinge of how difficult this can be.
Don't feel condemned if you are struggling with your thoughts at this moment. Don't worry if it takes effort for many days to come. Condemnation only weakens you; it never helps the process. Anytime we recognize that we are allowing wrong thoughts into our minds, we should ask God to forgive us and continue pressing on towards our goal.
Celebrate EVERY victory because it helps you to not feel overwhelmed by what still remains to be conquered, and remember that God is very patient and long suffering. He is understanding and will continually help you down this path.
That takes lots of practice.